Prevent XSS in links which open a new browser window

24 files changed, 70 insertions, 70 deletions

diff --git a/apps/federatedfilesharing/templates/settings-admin.php b/apps/federatedfilesharing/templates/settings-admin.php
index 7fe1b5f62e6..8d04169ea89 100644
--- a/apps/federatedfilesharing/templates/settings-admin.php
+++ b/apps/federatedfilesharing/templates/settings-admin.php
@@ -8,7 +8,7 @@ script('federatedfilesharing', 'settings-admin');
 
 <div id="fileSharingSettings" class="followupsection">
 	<h3><?php p($l->t('Federated Cloud Sharing'));?></h3>
-	<a target="_blank" rel="noreferrer" class="icon-info svg"
+	<a target="_blank" rel="noreferrer noopener" class="icon-info svg"
 		title="<?php p($l->t('Open documentation'));?>"
 		href="<?php p(link_to_docs('admin-sharing-federated')); ?>"></a>
 	<p class="settings-hint"><?php p($l->t('Adjust how people can share between servers.')); ?></p>
diff --git a/apps/federatedfilesharing/templates/settings-personal.php b/apps/federatedfilesharing/templates/settings-personal.php
index 26365d2b70c..89f7b1eb1e7 100644
--- a/apps/federatedfilesharing/templates/settings-personal.php
+++ b/apps/federatedfilesharing/templates/settings-personal.php
@@ -43,7 +43,7 @@ style('federatedfilesharing', 'settings-personal');
 
 		<div class="hidden" id="oca-files-sharing-add-to-your-website-expanded">
 		<p style="margin: 10px 0">
-			<a target="_blank" rel="noreferrer" href="<?php p($_['reference']); ?>"
+			<a target="_blank" rel="noreferrer noopener" href="<?php p($_['reference']); ?>"
 				style="padding:10px;background-color:<?php p($_['color']); ?>;color:<?php p($_['textColor']); ?>;border-radius:3px;padding-left:4px;">
 				<span style="background-image:url(<?php p(\OC::$server->getURLGenerator()->getAbsoluteURL($_['logoPath'])); ?>);width:50px;height:30px;position:relative;top:8px;background-size:contain;display:inline-block;background-repeat:no-repeat; background-position: center center;"></span>
 				<?php p($l->t('Share with me via Nextcloud')); ?>
@@ -52,7 +52,7 @@ style('federatedfilesharing', 'settings-personal');
 
 		<p>
 			<?php p($l->t('HTML Code:')); ?>
-			<xmp><a target="_blank" rel="noreferrer" href="<?php p($_['reference']); ?>" style="padding:10px;background-color:<?php p($_['color']); ?>;color:<?php p($_['textColor']); ?>;border-radius:3px;padding-left:4px;">
+			<xmp><a target="_blank" rel="noreferrer noopener" href="<?php p($_['reference']); ?>" style="padding:10px;background-color:<?php p($_['color']); ?>;color:<?php p($_['textColor']); ?>;border-radius:3px;padding-left:4px;">
 <span style="background-image:url(<?php p(\OC::$server->getURLGenerator()->getAbsoluteURL($_['logoPath'])); ?>);width:50px;height:30px;position:relative;top:8px;background-size:contain;display:inline-block;background-repeat:no-repeat; background-position: center center;"></span>
 <?php p($l->t('Share with me via Nextcloud')); ?></a></xmp>
 		</p>
diff --git a/apps/files/templates/appnavigation.php b/apps/files/templates/appnavigation.php
index 6a7b4e4b11e..f3bf0334b55 100644
--- a/apps/files/templates/appnavigation.php
+++ b/apps/files/templates/appnavigation.php
@@ -42,7 +42,7 @@
 			</div>
 			<label for="webdavurl"><?php p($l->t('WebDAV'));?></label>
 			<input id="webdavurl" type="text" readonly="readonly" value="<?php p(\OCP\Util::linkToRemote('webdav')); ?>" />
-			<em><?php print_unescaped($l->t('Use this address to <a href="%s" target="_blank" rel="noreferrer">access your Files via WebDAV</a>', array(link_to_docs('user-webdav'))));?></em>
+			<em><?php print_unescaped($l->t('Use this address to <a href="%s" target="_blank" rel="noreferrer noopener">access your Files via WebDAV</a>', array(link_to_docs('user-webdav'))));?></em>
 		</div>
 	</div>
 </div>
diff --git a/apps/theming/lib/ThemingDefaults.php b/apps/theming/lib/ThemingDefaults.php
index 6ee546d2630..97e889a2140 100644
--- a/apps/theming/lib/ThemingDefaults.php
+++ b/apps/theming/lib/ThemingDefaults.php
@@ -134,7 +134,7 @@ class ThemingDefaults extends \OC_Defaults {
 	public function getShortFooter() {
 		$slogan = $this->getSlogan();
 		$footer = '<a href="'. $this->getBaseUrl() . '" target="_blank"' .
-			' rel="noreferrer">' .$this->getEntity() . '</a>'.
+			' rel="noreferrer noopener">' .$this->getEntity() . '</a>'.
 			($slogan !== '' ? ' – ' . $slogan : '');
 
 		return $footer;
diff --git a/apps/theming/tests/ThemingDefaultsTest.php b/apps/theming/tests/ThemingDefaultsTest.php
index abd85a612c9..6fbf3a2529d 100644
--- a/apps/theming/tests/ThemingDefaultsTest.php
+++ b/apps/theming/tests/ThemingDefaultsTest.php
@@ -217,7 +217,7 @@ class ThemingDefaultsTest extends TestCase {
 				['theming', 'slogan', $this->defaults->getSlogan(), 'Slogan'],
 			]);
 
-		$this->assertEquals('<a href="url" target="_blank" rel="noreferrer">Name</a> – Slogan', $this->template->getShortFooter());
+		$this->assertEquals('<a href="url" target="_blank" rel="noreferrer noopener">Name</a> – Slogan', $this->template->getShortFooter());
 	}
 
 	public function testGetShortFooterEmptySlogan() {
@@ -230,7 +230,7 @@ class ThemingDefaultsTest extends TestCase {
 				['theming', 'slogan', $this->defaults->getSlogan(), ''],
 			]);
 
-		$this->assertEquals('<a href="url" target="_blank" rel="noreferrer">Name</a>', $this->template->getShortFooter());
+		$this->assertEquals('<a href="url" target="_blank" rel="noreferrer noopener">Name</a>', $this->template->getShortFooter());
 	}
 
 	public function testgetColorPrimaryWithDefault() {
diff --git a/apps/user_ldap/templates/part.settingcontrols.php b/apps/user_ldap/templates/part.settingcontrols.php
index 3f7a53dd4dc..a418885f47e 100644
--- a/apps/user_ldap/templates/part.settingcontrols.php
+++ b/apps/user_ldap/templates/part.settingcontrols.php
@@ -3,7 +3,7 @@
 		<?php p($l->t('Test Configuration'));?>
 	</button>
 	<a href="<?php p(link_to_docs('admin-ldap')); ?>"
-		target="_blank" rel="noreferrer">
+		target="_blank" rel="noreferrer noopener">
 		<img src="<?php print_unescaped(image_path('', 'actions/info.svg')); ?>"
 			style="height:1.75ex" />
 		<?php p($l->t('Help'));?>
diff --git a/apps/user_ldap/templates/part.wizardcontrols.php b/apps/user_ldap/templates/part.wizardcontrols.php
index 2df1fd8d83f..89eb96827e6 100644
--- a/apps/user_ldap/templates/part.wizardcontrols.php
+++ b/apps/user_ldap/templates/part.wizardcontrols.php
@@ -9,7 +9,7 @@
 		<?php p($l->t('Continue'));?>
 	</button>
 	<a href="<?php p(link_to_docs('admin-ldap')); ?>"
-		target="_blank" rel="noreferrer">
+		target="_blank" rel="noreferrer noopener">
 		<img src="<?php print_unescaped(image_path('', 'actions/info.svg')); ?>"
 			style="height:1.75ex" />
 		<span class="ldap_grey"><?php p($l->t('Help'));?></span>
diff --git a/apps/workflowengine/templates/admin.php b/apps/workflowengine/templates/admin.php
index 4f4dab4043f..e9873f8f289 100644
--- a/apps/workflowengine/templates/admin.php
+++ b/apps/workflowengine/templates/admin.php
@@ -25,7 +25,7 @@
 <div id="<?php p($_['appid']); ?>" class="section workflowengine">
 	<h2 class="inlineblock"><?php p($_['heading']); ?></h2>
 	<?php if (!empty($_['docs'])): ?>
-		<a target="_blank" rel="noreferrer" class="icon-info svg"
+		<a target="_blank" rel="noreferrer noopener" class="icon-info svg"
 		   title="<?php p($l->t('Open documentation'));?>"
 		   href="<?php p(link_to_docs($_['docs'])); ?>">
 		</a>
diff --git a/core/js/setupchecks.js b/core/js/setupchecks.js
index 5e8ef9e6961..99e3c72d2d4 100644
--- a/core/js/setupchecks.js
+++ b/core/js/setupchecks.js
@@ -66,7 +66,7 @@
 				if (xhr.status !== 207) {
 					var docUrl = placeholderUrl.replace('PLACEHOLDER', 'admin-setup-well-known-URL');
 					messages.push({
-						msg: t('core', 'Your web server is not set up properly to resolve "{url}". Further information can be found in our <a target="_blank" rel="noreferrer" href="{docLink}">documentation</a>.', { docLink: docUrl, url: url }),
+						msg: t('core', 'Your web server is not set up properly to resolve "{url}". Further information can be found in our <a target="_blank" rel="noreferrer noopener" href="{docLink}">documentation</a>.', { docLink: docUrl, url: url }),
 						type: OC.SetupChecks.MESSAGE_TYPE_INFO
 					});
 				}
@@ -100,13 +100,13 @@
 					}
 					if(!data.isMemcacheConfigured) {
 						messages.push({
-							msg: t('core', 'No memory cache has been configured. To enhance your performance please configure a memcache if available. Further information can be found in our <a target="_blank" rel="noreferrer" href="{docLink}">documentation</a>.', {docLink: data.memcacheDocs}),
+							msg: t('core', 'No memory cache has been configured. To enhance your performance please configure a memcache if available. Further information can be found in our <a target="_blank" rel="noreferrer noopener" href="{docLink}">documentation</a>.', {docLink: data.memcacheDocs}),
 							type: OC.SetupChecks.MESSAGE_TYPE_INFO
 						});
 					}
 					if(!data.isUrandomAvailable) {
 						messages.push({
-							msg: t('core', '/dev/urandom is not readable by PHP which is highly discouraged for security reasons. Further information can be found in our <a target="_blank" rel="noreferrer" href="{docLink}">documentation</a>.', {docLink: data.securityDocs}),
+							msg: t('core', '/dev/urandom is not readable by PHP which is highly discouraged for security reasons. Further information can be found in our <a target="_blank" rel="noreferrer noopener" href="{docLink}">documentation</a>.', {docLink: data.securityDocs}),
 							type: OC.SetupChecks.MESSAGE_TYPE_WARNING
 						});
 					}
@@ -118,19 +118,19 @@
 					}
 					if(data.phpSupported && data.phpSupported.eol) {
 						messages.push({
-							msg: t('core', 'You are currently running PHP {version}. We encourage you to upgrade your PHP version to take advantage of <a target="_blank" rel="noreferrer" href="{phpLink}">performance and security updates provided by the PHP Group</a> as soon as your distribution supports it.', {version: data.phpSupported.version, phpLink: 'https://secure.php.net/supported-versions.php'}),
+							msg: t('core', 'You are currently running PHP {version}. We encourage you to upgrade your PHP version to take advantage of <a target="_blank" rel="noreferrer noopener" href="{phpLink}">performance and security updates provided by the PHP Group</a> as soon as your distribution supports it.', {version: data.phpSupported.version, phpLink: 'https://secure.php.net/supported-versions.php'}),
 							type: OC.SetupChecks.MESSAGE_TYPE_INFO
 						});
 					}
 					if(!data.forwardedForHeadersWorking) {
 						messages.push({
-							msg: t('core', 'The reverse proxy headers configuration is incorrect, or you are accessing Nextcloud from a trusted proxy. If you are not accessing Nextcloud from a trusted proxy, this is a security issue and can allow an attacker to spoof their IP address as visible to Nextcloud. Further information can be found in our <a target="_blank" rel="noreferrer" href="{docLink}">documentation</a>.', {docLink: data.reverseProxyDocs}),
+							msg: t('core', 'The reverse proxy headers configuration is incorrect, or you are accessing Nextcloud from a trusted proxy. If you are not accessing Nextcloud from a trusted proxy, this is a security issue and can allow an attacker to spoof their IP address as visible to Nextcloud. Further information can be found in our <a target="_blank" rel="noreferrer noopener" href="{docLink}">documentation</a>.', {docLink: data.reverseProxyDocs}),
 							type: OC.SetupChecks.MESSAGE_TYPE_WARNING
 						});
 					}
 					if(!data.isCorrectMemcachedPHPModuleInstalled) {
 						messages.push({
-							msg: t('core', 'Memcached is configured as distributed cache, but the wrong PHP module "memcache" is installed. \\OC\\Memcache\\Memcached only supports "memcached" and not "memcache". See the <a target="_blank" rel="noreferrer" href="{wikiLink}">memcached wiki about both modules</a>.', {wikiLink: 'https://code.google.com/p/memcached/wiki/PHPClientComparison'}),
+							msg: t('core', 'Memcached is configured as distributed cache, but the wrong PHP module "memcache" is installed. \\OC\\Memcache\\Memcached only supports "memcached" and not "memcache". See the <a target="_blank" rel="noreferrer noopener" href="{wikiLink}">memcached wiki about both modules</a>.', {wikiLink: 'https://code.google.com/p/memcached/wiki/PHPClientComparison'}),
 							type: OC.SetupChecks.MESSAGE_TYPE_WARNING
 						});
 					}
@@ -138,7 +138,7 @@
 						messages.push({
 							msg: t(
 									'core',
-									'Some files have not passed the integrity check. Further information on how to resolve this issue can be found in our <a target="_blank" rel="noreferrer" href="{docLink}">documentation</a>. (<a href="{codeIntegrityDownloadEndpoint}">List of invalid files…</a> / <a href="{rescanEndpoint}">Rescan…</a>)',
+									'Some files have not passed the integrity check. Further information on how to resolve this issue can be found in our <a target="_blank" rel="noreferrer noopener" href="{docLink}">documentation</a>. (<a href="{codeIntegrityDownloadEndpoint}">List of invalid files…</a> / <a href="{rescanEndpoint}">Rescan…</a>)',
 									{
 										docLink: data.codeIntegrityCheckerDocumentation,
 										codeIntegrityDownloadEndpoint: OC.generateUrl('/settings/integrity/failed'),
@@ -152,7 +152,7 @@
 						messages.push({
 							msg: t(
 								'core',
-								'The PHP OPcache is not properly configured. <a target="_blank" rel="noreferrer" href="{docLink}">For better performance we recommend</a> to use following settings in the <code>php.ini</code>:',
+								'The PHP OPcache is not properly configured. <a target="_blank" rel="noreferrer noopener" href="{docLink}">For better performance we recommend</a> to use following settings in the <code>php.ini</code>:',
 								{
 									docLink: data.phpOpcacheDocumentation,
 								}
@@ -300,7 +300,7 @@
 					var minimumSeconds = 15552000;
 					if(isNaN(transportSecurityValidity) || transportSecurityValidity <= (minimumSeconds - 1)) {
 						messages.push({
-							msg: t('core', 'The "Strict-Transport-Security" HTTP header is not configured to at least "{seconds}" seconds. For enhanced security we recommend enabling HSTS as described in our <a href="{docUrl}" rel="noreferrer">security tips</a>.', {'seconds': minimumSeconds, docUrl: tipsUrl}),
+							msg: t('core', 'The "Strict-Transport-Security" HTTP header is not configured to at least "{seconds}" seconds. For enhanced security we recommend enabling HSTS as described in our <a href="{docUrl}" rel="noreferrer noopener">security tips</a>.', {'seconds': minimumSeconds, docUrl: tipsUrl}),
 							type: OC.SetupChecks.MESSAGE_TYPE_WARNING
 						});
 					}
diff --git a/core/js/tests/specs/setupchecksSpec.js b/core/js/tests/specs/setupchecksSpec.js
index 35279f3501e..3df676099b7 100644
--- a/core/js/tests/specs/setupchecksSpec.js
+++ b/core/js/tests/specs/setupchecksSpec.js
@@ -68,7 +68,7 @@ describe('OC.SetupChecks tests', function() {
 
 			async.done(function( data, s, x ){
 				expect(data).toEqual([{
-					msg: 'Your web server is not set up properly to resolve "/.well-known/caldav/". Further information can be found in our <a href="http://example.org/admin-setup-well-known-URL" rel="noreferrer">documentation</a>.',
+					msg: 'Your web server is not set up properly to resolve "/.well-known/caldav/". Further information can be found in our <a href="http://example.org/admin-setup-well-known-URL" rel="noreferrer noopener">documentation</a>.',
 					type: OC.SetupChecks.MESSAGE_TYPE_INFO
 				}]);
 				done();
@@ -166,7 +166,7 @@ describe('OC.SetupChecks tests', function() {
 						msg: 'This server has no working Internet connection: Multiple endpoints could not be reached. This means that some of the features like mounting external storage, notifications about updates or installation of third-party apps will not work. Accessing files remotely and sending of notification emails might not work, either. We suggest to enable Internet connection for this server if you want to have all features.',
 						type: OC.SetupChecks.MESSAGE_TYPE_WARNING
 					}, {
-						msg: 'No memory cache has been configured. To enhance your performance please configure a memcache if available. Further information can be found in our <a href="https://docs.nextcloud.com/server/go.php?to=admin-performance" rel="noreferrer">documentation</a>.',
+						msg: 'No memory cache has been configured. To enhance your performance please configure a memcache if available. Further information can be found in our <a href="https://docs.nextcloud.com/server/go.php?to=admin-performance" rel="noreferrer noopener">documentation</a>.',
 						type: OC.SetupChecks.MESSAGE_TYPE_INFO
 					}]);
 				done();
@@ -200,7 +200,7 @@ describe('OC.SetupChecks tests', function() {
 						type: OC.SetupChecks.MESSAGE_TYPE_WARNING
 					},
 					{
-						msg: 'No memory cache has been configured. To enhance your performance please configure a memcache if available. Further information can be found in our <a href="https://docs.nextcloud.com/server/go.php?to=admin-performance" rel="noreferrer">documentation</a>.',
+						msg: 'No memory cache has been configured. To enhance your performance please configure a memcache if available. Further information can be found in our <a href="https://docs.nextcloud.com/server/go.php?to=admin-performance" rel="noreferrer noopener">documentation</a>.',
 						type: OC.SetupChecks.MESSAGE_TYPE_INFO
 					}]);
 				done();
@@ -261,7 +261,7 @@ describe('OC.SetupChecks tests', function() {
 
 			async.done(function( data, s, x ){
 				expect(data).toEqual([{
-					msg: '/dev/urandom is not readable by PHP which is highly discouraged for security reasons. Further information can be found in our <a href="https://docs.owncloud.org/myDocs.html" rel="noreferrer">documentation</a>.',
+					msg: '/dev/urandom is not readable by PHP which is highly discouraged for security reasons. Further information can be found in our <a href="https://docs.owncloud.org/myDocs.html" rel="noreferrer noopener">documentation</a>.',
 					type: OC.SetupChecks.MESSAGE_TYPE_WARNING
 				}]);
 				done();
@@ -291,7 +291,7 @@ describe('OC.SetupChecks tests', function() {
 
 			async.done(function( data, s, x ){
 				expect(data).toEqual([{
-					msg: 'Memcached is configured as distributed cache, but the wrong PHP module "memcache" is installed. \\OC\\Memcache\\Memcached only supports "memcached" and not "memcache". See the <a href="https://code.google.com/p/memcached/wiki/PHPClientComparison" rel="noreferrer">memcached wiki about both modules</a>.',
+					msg: 'Memcached is configured as distributed cache, but the wrong PHP module "memcache" is installed. \\OC\\Memcache\\Memcached only supports "memcached" and not "memcache". See the <a href="https://code.google.com/p/memcached/wiki/PHPClientComparison" rel="noreferrer noopener">memcached wiki about both modules</a>.',
 					type: OC.SetupChecks.MESSAGE_TYPE_WARNING
 				}]);
 				done();
@@ -321,7 +321,7 @@ describe('OC.SetupChecks tests', function() {
 
 			async.done(function( data, s, x ){
 				expect(data).toEqual([{
-					msg: 'The reverse proxy headers configuration is incorrect, or you are accessing Nextcloud from a trusted proxy. If you are not accessing Nextcloud from a trusted proxy, this is a security issue and can allow an attacker to spoof their IP address as visible to Nextcloud. Further information can be found in our <a href="https://docs.owncloud.org/foo/bar.html" rel="noreferrer">documentation</a>.',
+					msg: 'The reverse proxy headers configuration is incorrect, or you are accessing Nextcloud from a trusted proxy. If you are not accessing Nextcloud from a trusted proxy, this is a security issue and can allow an attacker to spoof their IP address as visible to Nextcloud. Further information can be found in our <a href="https://docs.owncloud.org/foo/bar.html" rel="noreferrer noopener">documentation</a>.',
 					type: OC.SetupChecks.MESSAGE_TYPE_WARNING
 				}]);
 				done();
@@ -402,7 +402,7 @@ describe('OC.SetupChecks tests', function() {
 
 			async.done(function( data, s, x ){
 				expect(data).toEqual([{
-					msg: 'You are currently running PHP 5.4.0. We encourage you to upgrade your PHP version to take advantage of <a href="https://secure.php.net/supported-versions.php" rel="noreferrer">performance and security updates provided by the PHP Group</a> as soon as your distribution supports it.',
+					msg: 'You are currently running PHP 5.4.0. We encourage you to upgrade your PHP version to take advantage of <a href="https://secure.php.net/supported-versions.php" rel="noreferrer noopener">performance and security updates provided by the PHP Group</a> as soon as your distribution supports it.',
 					type: OC.SetupChecks.MESSAGE_TYPE_INFO
 				}]);
 				done();
@@ -433,7 +433,7 @@ describe('OC.SetupChecks tests', function() {
 
 			async.done(function( data, s, x ){
 				expect(data).toEqual([{
-						msg: 'The PHP OPcache is not properly configured. <a href="https://example.org/link/to/doc" rel="noreferrer">For better performance we recommend</a> to use following settings in the <code>php.ini</code>:' + "<pre><code>opcache.enable=1\nopcache.enable_cli=1\nopcache.interned_strings_buffer=8\nopcache.max_accelerated_files=10000\nopcache.memory_consumption=128\nopcache.save_comments=1\nopcache.revalidate_freq=1</code></pre>",
+						msg: 'The PHP OPcache is not properly configured. <a href="https://example.org/link/to/doc" rel="noreferrer noopener">For better performance we recommend</a> to use following settings in the <code>php.ini</code>:' + "<pre><code>opcache.enable=1\nopcache.enable_cli=1\nopcache.interned_strings_buffer=8\nopcache.max_accelerated_files=10000\nopcache.memory_consumption=128\nopcache.save_comments=1\nopcache.revalidate_freq=1</code></pre>",
 						type: OC.SetupChecks.MESSAGE_TYPE_INFO
 					}]);
 				done();
@@ -617,7 +617,7 @@ describe('OC.SetupChecks tests', function() {
 
 		async.done(function( data, s, x ){
 			expect(data).toEqual([{
-				msg: 'The "Strict-Transport-Security" HTTP header is not configured to at least "15552000" seconds. For enhanced security we recommend enabling HSTS as described in our <a rel="noreferrer" href="http://localhost/index.php/settings/admin/tips-tricks">security tips</a>.',
+				msg: 'The "Strict-Transport-Security" HTTP header is not configured to at least "15552000" seconds. For enhanced security we recommend enabling HSTS as described in our <a rel="noreferrer noopener" href="http://localhost/index.php/settings/admin/tips-tricks">security tips</a>.',
 				type: OC.SetupChecks.MESSAGE_TYPE_WARNING
 			}]);
 			done();
@@ -642,7 +642,7 @@ describe('OC.SetupChecks tests', function() {
 
 		async.done(function( data, s, x ){
 			expect(data).toEqual([{
-				msg: 'The "Strict-Transport-Security" HTTP header is not configured to at least "15552000" seconds. For enhanced security we recommend enabling HSTS as described in our <a rel="noreferrer" href="http://localhost/index.php/settings/admin/tips-tricks">security tips</a>.',
+				msg: 'The "Strict-Transport-Security" HTTP header is not configured to at least "15552000" seconds. For enhanced security we recommend enabling HSTS as described in our <a rel="noreferrer noopener" href="http://localhost/index.php/settings/admin/tips-tricks">security tips</a>.',
 				type: OC.SetupChecks.MESSAGE_TYPE_WARNING
 			}]);
 			done();
@@ -667,7 +667,7 @@ describe('OC.SetupChecks tests', function() {
 
 		async.done(function( data, s, x ){
 			expect(data).toEqual([{
-				msg: 'The "Strict-Transport-Security" HTTP header is not configured to at least "15552000" seconds. For enhanced security we recommend enabling HSTS as described in our <a rel="noreferrer" href="http://localhost/index.php/settings/admin/tips-tricks">security tips</a>.',
+				msg: 'The "Strict-Transport-Security" HTTP header is not configured to at least "15552000" seconds. For enhanced security we recommend enabling HSTS as described in our <a rel="noreferrer noopener" href="http://localhost/index.php/settings/admin/tips-tricks">security tips</a>.',
 				type: OC.SetupChecks.MESSAGE_TYPE_WARNING
 			}]);
 			done();
diff --git a/core/templates/installation.php b/core/templates/installation.php
index 6a0e3f93857..0d274f0f881 100644
--- a/core/templates/installation.php
+++ b/core/templates/installation.php
@@ -30,7 +30,7 @@ script('core', [
 		<legend><strong><?php p($l->t('Security warning'));?></strong></legend>
 		<p><?php p($l->t('Your data directory and files are probably accessible from the internet because the .htaccess file does not work.'));?><br>
 		<?php print_unescaped($l->t(
-			'For information how to properly configure your server, please see the <a href="%s" target="_blank" rel="noreferrer">documentation</a>.',
+			'For information how to properly configure your server, please see the <a href="%s" target="_blank" rel="noreferrer noopener">documentation</a>.',
 			link_to_docs('admin-install')
 		)); ?></p>
 	</fieldset>
@@ -84,7 +84,7 @@ script('core', [
 		<p class="info">
 			<?php p($l->t( 'Only %s is available.', array($label) )); ?>
 			<?php p($l->t( 'Install and activate additional PHP modules to choose other database types.' )); ?><br>
-			<a href="<?php print_unescaped(link_to_docs('admin-source_install')); ?>" target="_blank" rel="noreferrer">
+			<a href="<?php print_unescaped(link_to_docs('admin-source_install')); ?>" target="_blank" rel="noreferrer noopener">
 				<?php p($l->t( 'For more details check out the documentation.' )); ?> ↗</a>
 		</p>
 		<input type="hidden" id="dbtype" name="dbtype" value="<?php p($type) ?>">
@@ -166,6 +166,6 @@ script('core', [
 	<p class="info">
 		<span class="icon-info-white"></span>
 		<?php p($l->t('Need help?'));?>
-		<a target="_blank" rel="noreferrer" href="<?php p(link_to_docs('admin-install')); ?>"><?php p($l->t('See the documentation'));?> ↗</a>
+		<a target="_blank" rel="noreferrer noopener" href="<?php p(link_to_docs('admin-install')); ?>"><?php p($l->t('See the documentation'));?> ↗</a>
 	</p>
 </form>
diff --git a/core/templates/layout.noscript.warning.php b/core/templates/layout.noscript.warning.php
index c7776bd33c4..7d7a32bfbf4 100644
--- a/core/templates/layout.noscript.warning.php
+++ b/core/templates/layout.noscript.warning.php
@@ -3,7 +3,7 @@
 		<div>
 			<?php print_unescaped(str_replace(
 					['{linkstart}', '{linkend}'],
-					['<a href="https://www.enable-javascript.com/" target="_blank" rel="noreferrer">', '</a>'],
+					['<a href="https://www.enable-javascript.com/" target="_blank" rel="noreferrer noopener">', '</a>'],
 					$l->t('This application requires JavaScript for correct operation. Please {linkstart}enable JavaScript{linkend} and reload the page.')
 				)); ?>
 		</div>
diff --git a/core/templates/update.use-cli.php b/core/templates/update.use-cli.php
index d30e15c8573..06d7e284907 100644
--- a/core/templates/update.use-cli.php
+++ b/core/templates/update.use-cli.php
@@ -8,7 +8,7 @@
 				p($l->t('Please use the command line updater because automatic updating is disabled in the config.php.'));
 			} ?><br><br>
 			<?php
-			print_unescaped($l->t('For help, see the  <a target="_blank" rel="noreferrer" href="%s">documentation</a>.', [link_to_docs('admin-cli-upgrade')])); ?><br><br>
+			print_unescaped($l->t('For help, see the  <a target="_blank" rel="noreferrer noopener" href="%s">documentation</a>.', [link_to_docs('admin-cli-upgrade')])); ?><br><br>
 		</div>
 	</div>
 
diff --git a/lib/private/Installer.php b/lib/private/Installer.php
index d5082a7fad2..0f7217e0810 100644
--- a/lib/private/Installer.php
+++ b/lib/private/Installer.php
@@ -548,7 +548,7 @@ class Installer {
 			} catch (TableExistsException $e) {
 				throw new HintException(
 					'Failed to enable app ' . $app,
-					'Please ask for help via one of our <a href="https://nextcloud.com/support/" target="_blank" rel="noreferrer">support channels</a>.',
+					'Please ask for help via one of our <a href="https://nextcloud.com/support/" target="_blank" rel="noreferrer noopener">support channels</a>.',
 					0, $e
 				);
 			}
diff --git a/lib/private/legacy/defaults.php b/lib/private/legacy/defaults.php
index adfbe71377d..d2f639959cf 100644
--- a/lib/private/legacy/defaults.php
+++ b/lib/private/legacy/defaults.php
@@ -235,7 +235,7 @@ class OC_Defaults {
 			$footer = $this->theme->getShortFooter();
 		} else {
 			$footer = '<a href="'. $this->getBaseUrl() . '" target="_blank"' .
-				' rel="noreferrer">' .$this->getEntity() . '</a>'.
+				' rel="noreferrer noopener">' .$this->getEntity() . '</a>'.
 				' – ' . $this->getSlogan();
 		}
 
diff --git a/settings/templates/apps.php b/settings/templates/apps.php
index 91a73fcbe56..f609adb03b3 100644
--- a/settings/templates/apps.php
+++ b/settings/templates/apps.php
@@ -24,7 +24,7 @@ script(
 
 <?php if($_['appstoreEnabled']): ?>
 	<li>
-		<a class="app-external icon-info" target="_blank" rel="noreferrer" href="https://docs.nextcloud.org/server/12/developer_manual/"><?php p($l->t('Developer documentation'));?> ↗</a>
+		<a class="app-external icon-info" target="_blank" rel="noreferrer noopener" href="https://docs.nextcloud.org/server/12/developer_manual/"><?php p($l->t('Developer documentation'));?> ↗</a>
 	</li>
 <?php endif; ?>
 </script>
@@ -44,7 +44,7 @@ script(
 	<div class="app-image app-image-icon"></div>
 	<div class="app-name">
 		{{#if detailpage}}
-			<a href="{{detailpage}}" target="_blank" rel="noreferrer">{{name}}</a>
+			<a href="{{detailpage}}" target="_blank" rel="noreferrer noopener">{{name}}</a>
 		{{else}}
 			{{name}}
 		{{/if}}
@@ -90,7 +90,7 @@ script(
 	{{/if}}
 	<h2 class="app-name">
 		{{#if detailpage}}
-			<a href="{{detailpage}}" target="_blank" rel="noreferrer">{{name}}</a>
+			<a href="{{detailpage}}" target="_blank" rel="noreferrer noopener">{{name}}</a>
 		{{else}}
 			{{name}}
 		{{/if}}
@@ -105,7 +105,7 @@ script(
 
 	<div class="app-description-container hidden">
 		<div class="app-version">{{version}}</div>
-		{{#if profilepage}}<a href="{{profilepage}}" target="_blank" rel="noreferrer">{{/if}}
+		{{#if profilepage}}<a href="{{profilepage}}" target="_blank" rel="noreferrer noopener">{{/if}}
 		<div class="app-author"><?php p($l->t('by %s', ['{{author}}']));?>
 			{{#if licence}}
 			(<?php p($l->t('%s-licensed', ['{{licence}}'])); ?>)
@@ -119,30 +119,30 @@ script(
 			<?php p($l->t("Documentation:"));?>
 			{{#if documentation.user}}
 			<span class="userDocumentation">
-			<a id="userDocumentation" class="appslink" href="{{documentation.user}}" target="_blank" rel="noreferrer"><?php p($l->t('User documentation'));?> ↗</a>
+			<a id="userDocumentation" class="appslink" href="{{documentation.user}}" target="_blank" rel="noreferrer noopener"><?php p($l->t('User documentation'));?> ↗</a>
 			</span>
 			{{/if}}
 
 			{{#if documentation.admin}}
 			<span class="adminDocumentation">
-			<a id="adminDocumentation" class="appslink" href="{{documentation.admin}}" target="_blank" rel="noreferrer"><?php p($l->t('Admin documentation'));?> ↗</a>
+			<a id="adminDocumentation" class="appslink" href="{{documentation.admin}}" target="_blank" rel="noreferrer noopener"><?php p($l->t('Admin documentation'));?> ↗</a>
 			</span>
 			{{/if}}
 
 			{{#if documentation.developer}}
 			<span class="developerDocumentation">
-			<a id="developerDocumentation" class="appslink" href="{{documentation.developer}}" target="_blank" rel="noreferrer"><?php p($l->t('Developer documentation'));?> ↗</a>
+			<a id="developerDocumentation" class="appslink" href="{{documentation.developer}}" target="_blank" rel="noreferrer noopener"><?php p($l->t('Developer documentation'));?> ↗</a>
 			</span>
 			{{/if}}
 		</p>
 		{{/if}}
 
 		{{#if website}}
-		<a id="userDocumentation" class="appslink" href="{{website}}" target="_blank" rel="noreferrer"><?php p($l->t('Visit website'));?> ↗</a>
+		<a id="userDocumentation" class="appslink" href="{{website}}" target="_blank" rel="noreferrer noopener"><?php p($l->t('Visit website'));?> ↗</a>
 		{{/if}}
 
 		{{#if bugs}}
-		<a id="adminDocumentation" class="appslink" href="{{bugs}}" target="_blank" rel="noreferrer"><?php p($l->t('Report a bug'));?> ↗</a>
+		<a id="adminDocumentation" class="appslink" href="{{bugs}}" target="_blank" rel="noreferrer noopener"><?php p($l->t('Report a bug'));?> ↗</a>
 		{{/if}}
 	</div><!-- end app-description-container -->
 	<div class="app-description-toggle-show" role="link"><?php p($l->t("Show description …"));?></div>
diff --git a/settings/templates/help.php b/settings/templates/help.php
index f849ea0f427..3f042254f83 100644
--- a/settings/templates/help.php
+++ b/settings/templates/help.php
@@ -16,26 +16,26 @@
 	<?php } ?>
 
 		<li>
-			<a href="https://docs.nextcloud.org" target="_blank" rel="noreferrer">
+			<a href="https://docs.nextcloud.org" target="_blank" rel="noreferrer noopener">
 				<?php p($l->t('Online documentation')); ?> ↗
 			</a>
 		</li>
 		<li>
-			<a href="https://help.nextcloud.com" target="_blank" rel="noreferrer">
+			<a href="https://help.nextcloud.com" target="_blank" rel="noreferrer noopener">
 				<?php p($l->t('Forum')); ?> ↗
 			</a>
 		</li>
 
 	<?php if($_['admin']) { ?>
 		<li>
-			<a href="https://nextcloud.com/support/" target="_blank" rel="noreferrer">
+			<a href="https://nextcloud.com/support/" target="_blank" rel="noreferrer noopener">
 				<?php p($l->t('Getting help')); ?> ↗
 			</a>
 		</li>
 	<?php } ?>
 
 	<li>
-		<a href="https://nextcloud.com/enterprise/" target="_blank" rel="noreferrer">
+		<a href="https://nextcloud.com/enterprise/" target="_blank" rel="noreferrer noopener">
 			<?php p($l->t('Commercial support')); ?> ↗
 		</a>
 	</li>
diff --git a/settings/templates/settings.development.notice.php b/settings/templates/settings.development.notice.php
index 2b08d341f1e..855c4dc26c7 100644
--- a/settings/templates/settings.development.notice.php
+++ b/settings/templates/settings.development.notice.php
@@ -7,9 +7,9 @@
 				'{linkclose}',
 			],
 			[
-				'<a href="https://nextcloud.com/contribute" target="_blank" rel="noreferrer">',
-				'<a href="https://github.com/nextcloud" target="_blank" rel="noreferrer">',
-				'<a href="https://www.gnu.org/licenses/agpl-3.0.html" target="_blank" rel="noreferrer">',
+				'<a href="https://nextcloud.com/contribute" target="_blank" rel="noreferrer noopener">',
+				'<a href="https://github.com/nextcloud" target="_blank" rel="noreferrer noopener">',
+				'<a href="https://www.gnu.org/licenses/agpl-3.0.html" target="_blank" rel="noreferrer noopener">',
 				'</a>',
 			],
 			$l->t('Developed by the {communityopen}Nextcloud community{linkclose}, the {githubopen}source code{linkclose} is licensed under the {licenseopen}AGPL{linkclose}.')
diff --git a/settings/templates/settings/admin/additional-mail.php b/settings/templates/settings/admin/additional-mail.php
index bce7e5adeee..adcc5293ff1 100644
--- a/settings/templates/settings/admin/additional-mail.php
+++ b/settings/templates/settings/admin/additional-mail.php
@@ -53,7 +53,7 @@ if ($_['mail_smtpmode'] === 'qmail') {
 <div class="section" id="mail_general_settings">
 	<form id="mail_general_settings_form" class="mail_settings">
 		<h2><?php p($l->t('Email server'));?></h2>
-		<a target="_blank" rel="noreferrer" class="icon-info"
+		<a target="_blank" rel="noreferrer noopener" class="icon-info"
 		   title="<?php p($l->t('Open documentation'));?>"
 		   href="<?php p(link_to_docs('admin-email')); ?>"></a>
 		<p class="settings-hint"><?php p($l->t('It is important to set up this server to be able to send emails, like for password reset and notifications.')); ?></p>
diff --git a/settings/templates/settings/admin/encryption.php b/settings/templates/settings/admin/encryption.php
index 8fc4e9ae13b..d042f531da5 100644
--- a/settings/templates/settings/admin/encryption.php
+++ b/settings/templates/settings/admin/encryption.php
@@ -28,7 +28,7 @@
 
 <div class="section" id='encryptionAPI'>
 	<h2><?php p($l->t('Server-side encryption')); ?></h2>
-	<a target="_blank" rel="noreferrer" class="icon-info"
+	<a target="_blank" rel="noreferrer noopener" class="icon-info"
 	   title="<?php p($l->t('Open documentation'));?>"
 	   href="<?php p(link_to_docs('admin-encryption')); ?>"></a>
 	<p class="settings-hint"><?php p($l->t('Server-side encryption makes it possible to encrypt files which are uploaded to this server. This comes with limitations like a performance penalty, so enable this only if needed.')); ?></p>
diff --git a/settings/templates/settings/admin/server.php b/settings/templates/settings/admin/server.php
index ab30f8e7700..2805eb72ce1 100644
--- a/settings/templates/settings/admin/server.php
+++ b/settings/templates/settings/admin/server.php
@@ -36,7 +36,7 @@
 			?>
 			<li>
 				<?php p($l->t('PHP does not seem to be setup properly to query system environment variables. The test with getenv("PATH") only returns an empty response.')); ?><br>
-				<?php print_unescaped($l->t('Please check the <a target="_blank" rel="noreferrer" href="%s">installation documentation ↗</a> for PHP configuration notes and the PHP configuration of your server, especially when using php-fpm.', link_to_docs('admin-php-fpm'))); ?>
+				<?php print_unescaped($l->t('Please check the <a target="_blank" rel="noreferrer noopener" href="%s">installation documentation ↗</a> for PHP configuration notes and the PHP configuration of your server, especially when using php-fpm.', link_to_docs('admin-php-fpm'))); ?>
 			</li>
 			<?php
 		}
@@ -91,7 +91,7 @@
 		if ($_['fileLockingType'] === 'none') {
 			?>
 			<li>
-				<?php print_unescaped($l->t('Transactional file locking is disabled, this might lead to issues with race conditions. Enable \'filelocking.enabled\' in config.php to avoid these problems. See the <a target="_blank" rel="noreferrer" href="%s">documentation ↗</a> for more information.', link_to_docs('admin-transactional-locking'))); ?>
+				<?php print_unescaped($l->t('Transactional file locking is disabled, this might lead to issues with race conditions. Enable \'filelocking.enabled\' in config.php to avoid these problems. See the <a target="_blank" rel="noreferrer noopener" href="%s">documentation ↗</a> for more information.', link_to_docs('admin-transactional-locking'))); ?>
 			</li>
 			<?php
 		}
@@ -146,7 +146,7 @@
 		<ul class="warnings hidden"></ul>
 		<ul class="info hidden"></ul>
 		<p class="hint hidden">
-			<?php print_unescaped($l->t('Please double check the <a target="_blank" rel="noreferrer" href="%s">installation guides ↗</a>, and check for any errors or warnings in the <a href="%s">log</a>.', [link_to_docs('admin-install'), \OC::$server->getURLGenerator()->linkToRoute('settings.AdminSettings.index', ['section' => 'logging'])] )); ?>
+			<?php print_unescaped($l->t('Please double check the <a target="_blank" rel="noreferrer noopener" href="%s">installation guides ↗</a>, and check for any errors or warnings in the <a href="%s">log</a>.', [link_to_docs('admin-install'), \OC::$server->getURLGenerator()->linkToRoute('settings.AdminSettings.index', ['section' => 'logging'])] )); ?>
 		</p>
 	</div>
 	<div id="security-warning-state">
@@ -176,7 +176,7 @@
 			<?php p($l->t("Background job didn’t run yet!"));
 		endif; ?>
 	</p>
-	<a target="_blank" rel="noreferrer" class="icon-info"
+	<a target="_blank" rel="noreferrer noopener" class="icon-info"
 	   title="<?php p($l->t('Open documentation'));?>"
 	   href="<?php p(link_to_docs('admin-background-jobs')); ?>"></a>
 
@@ -223,5 +223,5 @@
 <div class="section">
 	<!-- should be the last part, so Updater can follow if enabled (it has no heading therefore). -->
 	<h2><?php p($l->t('Version'));?></h2>
-	<p><strong><a href="<?php print_unescaped($theme->getBaseUrl()); ?>" rel="noreferrer" target="_blank"><?php p($theme->getTitle()); ?></a> <?php p(OC_Util::getHumanVersion()) ?></strong></p>
+	<p><strong><a href="<?php print_unescaped($theme->getBaseUrl()); ?>" rel="noreferrer noopener" target="_blank"><?php p($theme->getTitle()); ?></a> <?php p(OC_Util::getHumanVersion()) ?></strong></p>
 </div>
diff --git a/settings/templates/settings/admin/sharing.php b/settings/templates/settings/admin/sharing.php
index 9c9e8c07809..156e8ddd81d 100644
--- a/settings/templates/settings/admin/sharing.php
+++ b/settings/templates/settings/admin/sharing.php
@@ -28,7 +28,7 @@
 
 <div class="section" id="shareAPI">
 	<h2><?php p($l->t('Sharing'));?></h2>
-	<a target="_blank" rel="noreferrer" class="icon-info"
+	<a target="_blank" rel="noreferrer noopener" class="icon-info"
 	   title="<?php p($l->t('Open documentation'));?>"
 	   href="<?php p(link_to_docs('admin-sharing')); ?>"></a>
         <p class="settings-hint"><?php p($l->t('As admin you can fine-tune the sharing behavior. Please see the documentation for more information.'));?></p>
diff --git a/settings/templates/settings/admin/tipstricks.php b/settings/templates/settings/admin/tipstricks.php
index c18c7f25f39..cf5c6c71104 100644
--- a/settings/templates/settings/admin/tipstricks.php
+++ b/settings/templates/settings/admin/tipstricks.php
@@ -37,15 +37,15 @@
 			<li>
 				<?php p($l->t('SQLite is currently being used as the backend database. For larger installations we recommend that you switch to a different database backend.')); ?><br>
 				<?php p($l->t('This is particularly recommended when using the desktop client for file synchronisation.')); ?><br>
-				<?php print_unescaped($l->t('To migrate to another database use the command line tool: \'occ db:convert-type\', or see the <a target="_blank" rel="noreferrer" href="%s">documentation ↗</a>.', link_to_docs('admin-db-conversion') )); ?>
+				<?php print_unescaped($l->t('To migrate to another database use the command line tool: \'occ db:convert-type\', or see the <a target="_blank" rel="noreferrer noopener" href="%s">documentation ↗</a>.', link_to_docs('admin-db-conversion') )); ?>
 			</li>
 		<?php } ?>
-		<li><a target="_blank" rel="noreferrer" href="<?php p(link_to_docs('admin-backup')); ?>"><?php p($l->t('How to do backups'));?> ↗</a></li>
-		<li><a target="_blank" rel="noreferrer" href="<?php p(link_to_docs('admin-monitoring')); ?>"><?php p($l->t('Advanced monitoring'));?> ↗</a></li>
-		<li><a target="_blank" rel="noreferrer" href="<?php p(link_to_docs('admin-performance')); ?>"><?php p($l->t('Performance tuning'));?> ↗</a></li>
-		<li><a target="_blank" rel="noreferrer" href="<?php p(link_to_docs('admin-config')); ?>"><?php p($l->t('Improving the config.php'));?> ↗</a></li>
-		<li><a target="_blank" rel="noreferrer" href="<?php p(link_to_docs('developer-theming')); ?>"><?php p($l->t('Theming'));?> ↗</a></li>
-		<li><a target="_blank" rel="noreferrer" href="https://scan.nextcloud.com"><?php p($l->t('Check the security of your Nextcloud over our security scan'));?> ↗</a></li>
-		<li><a target="_blank" rel="noreferrer" href="<?php p(link_to_docs('admin-security')); ?>"><?php p($l->t('Hardening and security guidance'));?> ↗</a></li>
+		<li><a target="_blank" rel="noreferrer noopener" href="<?php p(link_to_docs('admin-backup')); ?>"><?php p($l->t('How to do backups'));?> ↗</a></li>
+		<li><a target="_blank" rel="noreferrer noopener" href="<?php p(link_to_docs('admin-monitoring')); ?>"><?php p($l->t('Advanced monitoring'));?> ↗</a></li>
+		<li><a target="_blank" rel="noreferrer noopener" href="<?php p(link_to_docs('admin-performance')); ?>"><?php p($l->t('Performance tuning'));?> ↗</a></li>
+		<li><a target="_blank" rel="noreferrer noopener" href="<?php p(link_to_docs('admin-config')); ?>"><?php p($l->t('Improving the config.php'));?> ↗</a></li>
+		<li><a target="_blank" rel="noreferrer noopener" href="<?php p(link_to_docs('developer-theming')); ?>"><?php p($l->t('Theming'));?> ↗</a></li>
+		<li><a target="_blank" rel="noreferrer noopener" href="https://scan.nextcloud.com"><?php p($l->t('Check the security of your Nextcloud over our security scan'));?> ↗</a></li>
+		<li><a target="_blank" rel="noreferrer noopener" href="<?php p(link_to_docs('admin-security')); ?>"><?php p($l->t('Hardening and security guidance'));?> ↗</a></li>
 	</ul>
 </div>
diff --git a/settings/templates/settings/personal/personal.info.php b/settings/templates/settings/personal/personal.info.php
index d6f6061ebf2..04315d8cea0 100644
--- a/settings/templates/settings/personal/personal.info.php
+++ b/settings/templates/settings/personal/personal.info.php
@@ -338,7 +338,7 @@ vendor_style('jcrop/css/jquery.Jcrop');
 					<?php endforeach;?>
 				</select>
 				<a href="https://www.transifex.com/nextcloud/nextcloud/"
-					target="_blank" rel="noreferrer">
+					target="_blank" rel="noreferrer noopener">
 					<em><?php p($l->t('Help translate'));?></em>
 				</a>
 			</form>