diff --git a/components/com_users/controllers/user.php b/components/com_users/controllers/user.php
index 593e5a699e605..4a478d65d8e1d 100644
--- a/components/com_users/controllers/user.php
+++ b/components/com_users/controllers/user.php
@@ -210,7 +210,7 @@ public function logout()
 			// Don't redirect to an external URL.
 			if (!JUri::isInternal($return))
 			{
-				$return = '';
+				$return = 'index.php';
 			}
 		}
 
diff --git a/libraries/src/Uri/Uri.php b/libraries/src/Uri/Uri.php
index 535c465dca059..c77ecbee553b5 100644
--- a/libraries/src/Uri/Uri.php
+++ b/libraries/src/Uri/Uri.php
@@ -270,6 +270,59 @@ public function setPath($path)
 	public static function isInternal($url)
 	{
 		$uri = static::getInstance($url);
+
+		if ($uri->getScheme())
+		{
+			/*
+			 * The supplied URL contains a scheme, a host and probably also a port.
+			 * In order to allow URLs as internal even if they use a different scheme we have to replace the scheme etc. for the following tests accordingly
+			 * if the host in the supplied URL is identical to the host in our base.
+			 */
+			$baseuri = static::getInstance(static::base());
+
+			if ($uri->getHost() == $baseuri->getHost())
+			{
+				$uScheme = $uri->getScheme();
+				$uPort = $uri->getPort();
+				$bScheme = $baseuri->getScheme();
+				$bPort = $baseuri->getPort();
+
+				if ($uScheme == $bScheme)
+				{
+					/*
+					 * The supplied URL contains the same scheme as our base URL, so the scheme needs not to be changed for the following tests.
+					 * But we might have different ports given in the supplied URL and in our base URL:
+					 * - supplied URL: no port, our base URL: port 80 (HTTP) or 443 (HTTPS)
+					 * - supplied URL: port 80 (HTTP) or 443 (HTTPS), our base URL: no port
+					 * In these two cases we have to replace the port in the supplied URL with the port from our base URL.
+					 */
+					if ((!$uPort && (($bScheme == 'http' && $bPort == 80) || ($bScheme == 'https' && $bPort == 443)))
+						|| (!$bPort && (($uScheme == 'http' && $uPort == 80) || ($uScheme == 'https' && $uPort == 443))))
+					{
+						$uri->setPort($bPort);
+					}
+				}
+				else
+				{
+					/*
+					 * The supplied URL doesn't contain the same scheme as our base URL, so probably the scheme needs to be changed for the following tests.
+					 * Whether we change the scheme or not depends upon the following conditions:
+					 * - the scheme of the supplied URL is "http" and the port is either not specified or 80 and the scheme of our base URL is "https" and
+					 *   the port is either not specified or 443
+					 * - the scheme of the supplied URL is "https" and the port is either not specified or 443 and the scheme of our base URL is "http" and
+					 *   the port is either not specified or 80
+					 * In these two cases we have to replace the scheme and the port in the supplied URL with the scheme and the port from our base URL.
+					 */
+					if (($uScheme == 'http' && (!$uPort || $uPort == 80) && $bScheme == 'https' && (!$bPort || $bPort == 443))
+						|| ($uScheme == 'https' && (!$uPort || $uPort == 443) && $bScheme == 'http' && (!$bPort || $bPort == 80)))
+					{
+						$uri->setScheme($bScheme);
+						$uri->setPort($bPort);
+					}
+				}
+			}
+		}
+
 		$base = $uri->toString(array('scheme', 'host', 'port', 'path'));
 		$host = $uri->toString(array('scheme', 'host', 'port'));
 
diff --git a/modules/mod_login/helper.php b/modules/mod_login/helper.php
index fc31d5444b606..29b818ebc8a85 100644
--- a/modules/mod_login/helper.php
+++ b/modules/mod_login/helper.php
@@ -29,11 +29,9 @@ public static function getReturnUrl($params, $type)
 		$app  = JFactory::getApplication();
 		$item = $app->getMenu()->getItem($params->get($type));
 
-		// Stay on the same page
-		$url = JUri::getInstance()->toString();
-
 		if ($item)
 		{
+			// Continue with the redirection page configured
 			$lang = '';
 
 			if ($item->language !== '*' && JLanguageMultilang::isEnabled())
@@ -42,6 +40,27 @@ public static function getReturnUrl($params, $type)
 			}
 
 			$url = 'index.php?Itemid=' . $item->id . $lang;
+
+			// Check whether encrypted login form is enabled
+			if ($params->get('usesecure'))
+			{
+				// Login: access to redirection page via HTTPS, logout: access to redirection page via HTTP
+				$url = JRoute::_($url, true, ($type == 'login') ? 1 : 2);
+			}
+		}
+		else
+		{
+			// Stay on the same page
+			$url = JUri::getInstance();
+
+			// Check whether encrypted login form is enabled
+			if ($params->get('usesecure'))
+			{
+				// Login: access page via HTTPS, logout: access page via HTTP
+				$url->setScheme(($type == 'login') ? 'https' : 'http');
+			}
+			
+			$url = $url->toString();
 		}
 
 		return base64_encode($url);
diff --git a/tests/unit/suites/libraries/joomla/uri/JURITest.php b/tests/unit/suites/libraries/joomla/uri/JURITest.php
index f81b49ed6641d..1e0255d4a2054 100644
--- a/tests/unit/suites/libraries/joomla/uri/JURITest.php
+++ b/tests/unit/suites/libraries/joomla/uri/JURITest.php
@@ -29,6 +29,48 @@ class JUriTest extends \PHPUnit\Framework\TestCase
 	 */
 	protected $backupServer;
 
+	/**
+	 * Set up JUri environment depending upon arguments.
+	 * Allows to replace the environment for some tests.
+	 *
+	 * @param string $httpHost
+	 * @param bool   $https
+	 * @param string $scriptName
+	 * @param string $query
+	 * @param string $fragment
+	 *
+	 * @return void
+	 *
+	 * @since   11.1
+	 */
+	private function setUpLocal($httpHost, $https, $scriptName, $query = null, $fragment = null)
+	{
+		JUri::reset();
+
+		$_SERVER['HTTP_HOST'] = $httpHost;
+		if ($https)
+		{
+			$_SERVER['HTTPS'] = 'on';
+		}
+		else
+		{
+			unset($_SERVER['HTTPS']);
+		}
+		$_SERVER['SCRIPT_NAME'] = $scriptName;
+		$_SERVER['PHP_SELF'] = $scriptName;
+		$_SERVER['REQUEST_URI'] = $scriptName;
+		if (!empty($query))
+		{
+			$_SERVER['REQUEST_URI'] .= '?' . $query;
+		}
+		if (!empty($fragment))
+		{
+			$_SERVER['REQUEST_URI'] .= '#' . $fragment;
+		}
+
+		$this->object = new JUri;
+	}
+
 	/**
 	 * Sets up the fixture, for example, opens a network connection.
 	 * This method is called before a test is executed.
@@ -41,14 +83,7 @@ protected function setUp()
 	{
 		parent::setUp();
 		$this->backupServer = $_SERVER;
-		JUri::reset();
-
-		$_SERVER['HTTP_HOST'] = 'www.example.com:80';
-		$_SERVER['SCRIPT_NAME'] = '/joomla/index.php';
-		$_SERVER['PHP_SELF'] = '/joomla/index.php';
-		$_SERVER['REQUEST_URI'] = '/joomla/index.php?var=value 10';
-
-		$this->object = new JUri;
+		self::setUpLocal('www.example.com:80', false, '/joomla/index.php', 'var=value 10');
 	}
 
 	/**
@@ -216,6 +251,24 @@ public function testisInternalWithNoSchemeAndNotInternal()
 			JUri::isInternal('www.myotherexample.com'),
 			'www.myotherexample.com should NOT be resolved as internal'
 		);
+
+		self::setUpLocal('www.example.com', false, '/joomla/index.php', 'var=value 10');
+		$this->assertFalse(
+			JUri::isInternal('www.myotherexample.com'),
+			'www.myotherexample.com should NOT be resolved as internal'
+		);
+
+		self::setUpLocal('www.example.com:443', true, '/joomla/index.php', 'var=value 10');
+		$this->assertFalse(
+			JUri::isInternal('www.myotherexample.com'),
+			'www.myotherexample.com should NOT be resolved as internal'
+		);
+
+		self::setUpLocal('www.example.com', true, '/joomla/index.php', 'var=value 10');
+		$this->assertFalse(
+			JUri::isInternal('www.myotherexample.com'),
+			'www.myotherexample.com should NOT be resolved as internal'
+		);
 	}
 
 	/**
@@ -231,6 +284,24 @@ public function testisInternalWithNoSchemeAndNoHostnameAndNotInternal()
 			JUri::isInternal('myotherexample.com'),
 			'myotherexample.com should NOT be resolved as internal'
 		);
+
+		self::setUpLocal('www.example.com', false, '/joomla/index.php', 'var=value 10');
+		$this->assertFalse(
+			JUri::isInternal('myotherexample.com'),
+			'myotherexample.com should NOT be resolved as internal'
+		);
+
+		self::setUpLocal('www.example.com:443', true, '/joomla/index.php', 'var=value 10');
+		$this->assertFalse(
+			JUri::isInternal('myotherexample.com'),
+			'myotherexample.com should NOT be resolved as internal'
+		);
+
+		self::setUpLocal('www.example.com', true, '/joomla/index.php', 'var=value 10');
+		$this->assertFalse(
+			JUri::isInternal('myotherexample.com'),
+			'myotherexample.com should NOT be resolved as internal'
+		);
 	}
 
 	/**
@@ -244,7 +315,25 @@ public function testisInternalWithSchemeAndNotInternal()
 	{
 		$this->assertFalse(
 			JUri::isInternal('http://www.myotherexample.com'),
-			'http://www.myotherexample.com should NOT be resolved as  internal'
+			'http://www.myotherexample.com should NOT be resolved as internal'
+		);
+
+		self::setUpLocal('www.example.com', false, '/joomla/index.php', 'var=value 10');
+		$this->assertFalse(
+			JUri::isInternal('http://www.myotherexample.com'),
+			'http://www.myotherexample.com should NOT be resolved as internal'
+		);
+
+		self::setUpLocal('www.example.com:443', true, '/joomla/index.php', 'var=value 10');
+		$this->assertFalse(
+			JUri::isInternal('http://www.myotherexample.com'),
+			'http://www.myotherexample.com should NOT be resolved as internal'
+		);
+
+		self::setUpLocal('www.example.com', true, '/joomla/index.php', 'var=value 10');
+		$this->assertFalse(
+			JUri::isInternal('http://www.myotherexample.com'),
+			'http://www.myotherexample.com should NOT be resolved as internal'
 		);
 	}
 
@@ -261,6 +350,24 @@ public function testisInternalWhenInternalWithNoDomainOrScheme()
 			JUri::isInternal('index.php?option=com_something'),
 			'index.php?option=com_something should be internal'
 		);
+
+		self::setUpLocal('www.example.com', false, '/joomla/index.php', 'var=value 10');
+		$this->assertTrue(
+			JUri::isInternal('index.php?option=com_something'),
+			'index.php?option=com_something should be internal'
+		);
+
+		self::setUpLocal('www.example.com:443', true, '/joomla/index.php', 'var=value 10');
+		$this->assertTrue(
+			JUri::isInternal('index.php?option=com_something'),
+			'index.php?option=com_something should be internal'
+		);
+
+		self::setUpLocal('www.example.com', true, '/joomla/index.php', 'var=value 10');
+		$this->assertTrue(
+			JUri::isInternal('index.php?option=com_something'),
+			'index.php?option=com_something should be internal'
+		);
 	}
 
 	/**
@@ -276,6 +383,34 @@ public function testisInternalWhenInternalWithDomainAndSchemeAndPort()
 			JUri::isInternal(JUri::base() . 'index.php?option=com_something'),
 			JUri::base() . 'index.php?option=com_something should be internal'
 		);
+
+		self::setUpLocal('www.example.com:443', true, '/joomla/index.php', 'var=value 10');
+		$this->assertTrue(
+			JUri::isInternal(JUri::base() . 'index.php?option=com_something'),
+			JUri::base() . 'index.php?option=com_something should be internal'
+		);
+	}
+
+	/**
+	 * Test hardening of JUri::isInternal against non internal links
+	 *
+	 * @return void
+	 *
+	 * @covers JUri::isInternal
+	 */
+	public function testisInternalWhenInternalWithDomainAndSchemeAndNoPort()
+	{
+		self::setUpLocal('www.example.com', false, '/joomla/index.php', 'var=value 10');
+		$this->assertTrue(
+			JUri::isInternal(JUri::base() . 'index.php?option=com_something'),
+			JUri::base() . 'index.php?option=com_something should be internal'
+		);
+
+		self::setUpLocal('www.example.com', true, '/joomla/index.php', 'var=value 10');
+		$this->assertTrue(
+			JUri::isInternal(JUri::base() . 'index.php?option=com_something'),
+			JUri::base() . 'index.php?option=com_something should be internal'
+		);
 	}
 
 	/**
@@ -287,15 +422,35 @@ public function testisInternalWhenInternalWithDomainAndSchemeAndPort()
 	 */
 	public function testisInternalWhenInternalWithDomainAndSchemeAndPortNoSubFolder()
 	{
-		JUri::reset();
+		self::setUpLocal('www.example.com:80', false, '/index.php', 'var=value 10');
+		$this->assertTrue(
+			JUri::isInternal(JUri::base() . 'index.php?option=com_something'),
+			JUri::base() . 'index.php?option=com_something should be internal'
+		);
 
-		$_SERVER['HTTP_HOST'] = 'www.example.com:80';
-		$_SERVER['SCRIPT_NAME'] = '/index.php';
-		$_SERVER['PHP_SELF'] = '/index.php';
-		$_SERVER['REQUEST_URI'] = '/index.php?var=value 10';
+		self::setUpLocal('www.example.com:443', true, '/index.php', 'var=value 10');
+		$this->assertTrue(
+			JUri::isInternal(JUri::base() . 'index.php?option=com_something'),
+			JUri::base() . 'index.php?option=com_something should be internal'
+		);
+	}
 
-		$this->object = new JUri;
+	/**
+	 * Test hardening of JUri::isInternal against non internal links
+	 *
+	 * @return void
+	 *
+	 * @covers JUri::isInternal
+	 */
+	public function testisInternalWhenInternalWithDomainAndSchemeAndNoPortNoSubFolder()
+	{
+		self::setUpLocal('www.example.com', false, '/index.php', 'var=value 10');
+		$this->assertTrue(
+			JUri::isInternal(JUri::base() . 'index.php?option=com_something'),
+			JUri::base() . 'index.php?option=com_something should be internal'
+		);
 
+		self::setUpLocal('www.example.com', true, '/index.php', 'var=value 10');
 		$this->assertTrue(
 			JUri::isInternal(JUri::base() . 'index.php?option=com_something'),
 			JUri::base() . 'index.php?option=com_something should be internal'
@@ -315,6 +470,34 @@ public function testisInternalWhenNOTInternalWithDomainAndSchemeAndPortAndIndex(
 			JUri::isInternal('http://www.myotherexample.com/index.php?option=com_something'),
 			'http://www.myotherexample.com/index.php?option=com_something should NOT be internal'
 		);
+
+		self::setUpLocal('www.example.com:443', true, '/joomla/index.php', 'var=value 10');
+		$this->assertFalse(
+			JUri::isInternal('http://www.myotherexample.com/index.php?option=com_something'),
+			'http://www.myotherexample.com/index.php?option=com_something should NOT be internal'
+		);
+	}
+
+	/**
+	 * Test hardening of JUri::isInternal against non internal links
+	 *
+	 * @return void
+	 *
+	 * @covers JUri::isInternal
+	 */
+	public function testisInternalWhenNOTInternalWithDomainAndSchemeAndNoPortAndIndex()
+	{
+		self::setUpLocal('www.example.com', false, '/joomla/index.php', 'var=value 10');
+		$this->assertFalse(
+			JUri::isInternal('http://www.myotherexample.com/index.php?option=com_something'),
+			'http://www.myotherexample.com/index.php?option=com_something should NOT be internal'
+		);
+
+		self::setUpLocal('www.example.com', true, '/joomla/index.php', 'var=value 10');
+		$this->assertFalse(
+			JUri::isInternal('http://www.myotherexample.com/index.php?option=com_something'),
+			'http://www.myotherexample.com/index.php?option=com_something should NOT be internal'
+		);
 	}
 
 	/**
@@ -330,6 +513,24 @@ public function testisInternalWhenNOTInternalWithDomainAndNoSchemeAndPortAndInde
 			JUri::isInternal('www.myotherexample.com/index.php?option=com_something'),
 			'www.myotherexample.comindex.php?option=com_something should NOT be internal'
 		);
+
+		self::setUpLocal('www.example.com', false, '/joomla/index.php', 'var=value 10');
+		$this->assertFalse(
+			JUri::isInternal('www.myotherexample.com/index.php?option=com_something'),
+			'www.myotherexample.comindex.php?option=com_something should NOT be internal'
+		);
+
+		self::setUpLocal('www.example.com:443', true, '/joomla/index.php', 'var=value 10');
+		$this->assertFalse(
+			JUri::isInternal('www.myotherexample.com/index.php?option=com_something'),
+			'www.myotherexample.comindex.php?option=com_something should NOT be internal'
+		);
+
+		self::setUpLocal('www.example.com', true, '/joomla/index.php', 'var=value 10');
+		$this->assertFalse(
+			JUri::isInternal('www.myotherexample.com/index.php?option=com_something'),
+			'www.myotherexample.comindex.php?option=com_something should NOT be internal'
+		);
 	}
 
 	/**
@@ -345,6 +546,24 @@ public function testisInternal3rdPartyDevs()
 			JUri::isInternal('/customDevScript.php'),
 			'/customDevScript.php should NOT be internal'
 		);
+
+		self::setUpLocal('www.example.com', false, '/joomla/index.php', 'var=value 10');
+		$this->assertFalse(
+			JUri::isInternal('/customDevScript.php'),
+			'/customDevScript.php should NOT be internal'
+		);
+
+		self::setUpLocal('www.example.com:443', true, '/joomla/index.php', 'var=value 10');
+		$this->assertFalse(
+			JUri::isInternal('/customDevScript.php'),
+			'/customDevScript.php should NOT be internal'
+		);
+
+		self::setUpLocal('www.example.com', true, '/joomla/index.php', 'var=value 10');
+		$this->assertFalse(
+			JUri::isInternal('/customDevScript.php'),
+			'/customDevScript.php should NOT be internal'
+		);
 	}
 
 	/**
@@ -360,6 +579,24 @@ public function testAppendingOfBaseToTheEndOfTheUrl()
 			JUri::isInternal('/customDevScript.php?www.example.com'),
 			'/customDevScript.php?www.example.com should NOT be internal'
 		);
+
+		self::setUpLocal('www.example.com', false, '/joomla/index.php', 'var=value 10');
+		$this->assertFalse(
+			JUri::isInternal('/customDevScript.php?www.example.com'),
+			'/customDevScript.php?www.example.com should NOT be internal'
+		);
+
+		self::setUpLocal('www.example.com:443', true, '/joomla/index.php', 'var=value 10');
+		$this->assertFalse(
+			JUri::isInternal('/customDevScript.php?www.example.com'),
+			'/customDevScript.php?www.example.com should NOT be internal'
+		);
+
+		self::setUpLocal('www.example.com', true, '/joomla/index.php', 'var=value 10');
+		$this->assertFalse(
+			JUri::isInternal('/customDevScript.php?www.example.com'),
+			'/customDevScript.php?www.example.com should NOT be internal'
+		);
 	}
 
 	/**
@@ -375,6 +612,24 @@ public function testAppendingOfBaseToTheEndOfTheUrl2()
 			JUri::isInternal('www.otherexample.com/www.example.com'),
 			'www.otherexample.com/www.example.com should NOT be internal'
 		);
+
+		self::setUpLocal('www.example.com', false, '/joomla/index.php', 'var=value 10');
+		$this->assertFalse(
+			JUri::isInternal('www.otherexample.com/www.example.com'),
+			'www.otherexample.com/www.example.com should NOT be internal'
+		);
+
+		self::setUpLocal('www.example.com:443', true, '/joomla/index.php', 'var=value 10');
+		$this->assertFalse(
+			JUri::isInternal('www.otherexample.com/www.example.com'),
+			'www.otherexample.com/www.example.com should NOT be internal'
+		);
+
+		self::setUpLocal('www.example.com', true, '/joomla/index.php', 'var=value 10');
+		$this->assertFalse(
+			JUri::isInternal('www.otherexample.com/www.example.com'),
+			'www.otherexample.com/www.example.com should NOT be internal'
+		);
 	}
 
 	/**
@@ -390,6 +645,210 @@ public function testSchemeEmptyButHostAndPortMatch()
 			JUri::isInternal('www.example.com:80'),
 			'www.example.com:80 should be internal'
 		);
+
+		self::setUpLocal('www.example.com:443', true, '/joomla/index.php', 'var=value 10');
+		$this->assertTrue(
+			JUri::isInternal('www.example.com:443'),
+			'www.example.com:443 should be internal'
+		);
+	}
+
+	/**
+	 * Test hardening of JUri::isInternal against non internal links
+	 *
+	 * @return void
+	 *
+	 * @covers JUri::isInternal
+	 */
+	public function testSchemeHostMatchNoPort()
+	{
+		$this->assertTrue(
+			JUri::isInternal('http://www.example.com/joomla/index.php'),
+			'http://www.example.com/joomla/index.php should be internal'
+		);
+
+		self::setUpLocal('www.example.com', false, '/joomla/index.php', 'var=value 10');
+		$this->assertTrue(
+			JUri::isInternal('http://www.example.com/joomla/index.php'),
+			'http://www.example.com/joomla/index.php should be internal'
+		);
+
+		self::setUpLocal('www.example.com:443', true, '/joomla/index.php', 'var=value 10');
+		$this->assertTrue(
+			JUri::isInternal('https://www.example.com/joomla/index.php'),
+			'https://www.example.com/joomla/index.php should be internal'
+		);
+
+		self::setUpLocal('www.example.com', true, '/joomla/index.php', 'var=value 10');
+		$this->assertTrue(
+			JUri::isInternal('https://www.example.com/joomla/index.php'),
+			'https://www.example.com/joomla/index.php should be internal'
+		);
+	}
+
+	/**
+	 * Test hardening of JUri::isInternal against non internal links
+	 *
+	 * @return void
+	 *
+	 * @covers JUri::isInternal
+	 */
+	public function testSchemeDifferHostMatchNoPort()
+	{
+		$this->assertTrue(
+			JUri::isInternal('https://www.example.com/joomla/index.php'),
+			'https://www.example.com/joomla/index.php should be internal'
+		);
+
+		self::setUpLocal('www.example.com', false, '/joomla/index.php', 'var=value 10');
+		$this->assertTrue(
+			JUri::isInternal('https://www.example.com/joomla/index.php'),
+			'https://www.example.com/joomla/index.php should be internal'
+		);
+
+		self::setUpLocal('www.example.com:443', true, '/joomla/index.php', 'var=value 10');
+		$this->assertTrue(
+			JUri::isInternal('http://www.example.com/joomla/index.php'),
+			'http://www.example.com/joomla/index.php should be internal'
+		);
+
+		self::setUpLocal('www.example.com', true, '/joomla/index.php', 'var=value 10');
+		$this->assertTrue(
+			JUri::isInternal('http://www.example.com/joomla/index.php'),
+			'http://www.example.com/joomla/index.php should be internal'
+		);
+	}
+
+	/**
+	 * Test hardening of JUri::isInternal against non internal links
+	 *
+	 * @return void
+	 *
+	 * @covers JUri::isInternal
+	 */
+	public function testSchemeHostMatchStandardPort()
+	{
+		$this->assertTrue(
+			JUri::isInternal('http://www.example.com:80/joomla/index.php'),
+			'http://www.example.com:80/joomla/index.php should be internal'
+		);
+
+		self::setUpLocal('www.example.com', false, '/joomla/index.php', 'var=value 10');
+		$this->assertTrue(
+			JUri::isInternal('http://www.example.com:80/joomla/index.php'),
+			'http://www.example.com:80/joomla/index.php should be internal'
+		);
+
+		self::setUpLocal('www.example.com:443', true, '/joomla/index.php', 'var=value 10');
+		$this->assertTrue(
+			JUri::isInternal('https://www.example.com:443/joomla/index.php'),
+			'https://www.example.com:443/joomla/index.php should be internal'
+		);
+
+		self::setUpLocal('www.example.com', true, '/joomla/index.php', 'var=value 10');
+		$this->assertTrue(
+			JUri::isInternal('https://www.example.com:443/joomla/index.php'),
+			'https://www.example.com:443/joomla/index.php should be internal'
+		);
+	}
+
+	/**
+	 * Test hardening of JUri::isInternal against non internal links
+	 *
+	 * @return void
+	 *
+	 * @covers JUri::isInternal
+	 */
+	public function testSchemeDifferHostMatchStandardPort()
+	{
+		$this->assertTrue(
+			JUri::isInternal('https://www.example.com:443/joomla/index.php'),
+			'https://www.example.com:443/joomla/index.php should be internal'
+		);
+
+		self::setUpLocal('www.example.com', false, '/joomla/index.php', 'var=value 10');
+		$this->assertTrue(
+			JUri::isInternal('https://www.example.com:443/joomla/index.php'),
+			'https://www.example.com:443/joomla/index.php should be internal'
+		);
+
+		self::setUpLocal('www.example.com:443', true, '/joomla/index.php', 'var=value 10');
+		$this->assertTrue(
+			JUri::isInternal('http://www.example.com:80/joomla/index.php'),
+			'http://www.example.com:80/joomla/index.php should be internal'
+		);
+
+		self::setUpLocal('www.example.com', true, '/joomla/index.php', 'var=value 10');
+		$this->assertTrue(
+			JUri::isInternal('http://www.example.com:80/joomla/index.php'),
+			'http://www.example.com:80/joomla/index.php should be internal'
+		);
+	}
+
+	/**
+	 * Test hardening of JUri::isInternal against non internal links
+	 *
+	 * @return void
+	 *
+	 * @covers JUri::isInternal
+	 */
+	public function testSchemeHostMatchNonStandardPort()
+	{
+		$this->assertFalse(
+			JUri::isInternal('http://www.example.com:8080/joomla/index.php'),
+			'http://www.example.com:8080/joomla/index.php should NOT be internal'
+		);
+
+		self::setUpLocal('www.example.com', false, '/joomla/index.php', 'var=value 10');
+		$this->assertFalse(
+			JUri::isInternal('http://www.example.com:8080/joomla/index.php'),
+			'http://www.example.com:8080/joomla/index.php should NOT be internal'
+		);
+
+		self::setUpLocal('www.example.com:443', true, '/joomla/index.php', 'var=value 10');
+		$this->assertFalse(
+			JUri::isInternal('https://www.example.com:8443/joomla/index.php'),
+			'https://www.example.com:8443/joomla/index.php should NOT be internal'
+		);
+
+		self::setUpLocal('www.example.com', true, '/joomla/index.php', 'var=value 10');
+		$this->assertFalse(
+			JUri::isInternal('https://www.example.com:8443/joomla/index.php'),
+			'https://www.example.com:8443/joomla/index.php should NOT be internal'
+		);
+	}
+
+	/**
+	 * Test hardening of JUri::isInternal against non internal links
+	 *
+	 * @return void
+	 *
+	 * @covers JUri::isInternal
+	 */
+	public function testSchemeDifferHostMatchNonStandardPort()
+	{
+		$this->assertFalse(
+			JUri::isInternal('https://www.example.com:8443/joomla/index.php'),
+			'https://www.example.com:8443/joomla/index.php should NOT be internal'
+		);
+
+		self::setUpLocal('www.example.com', false, '/joomla/index.php', 'var=value 10');
+		$this->assertFalse(
+			JUri::isInternal('https://www.example.com:8443/joomla/index.php'),
+			'https://www.example.com:8443/joomla/index.php should NOT be internal'
+		);
+
+		self::setUpLocal('www.example.com:443', true, '/joomla/index.php', 'var=value 10');
+		$this->assertFalse(
+			JUri::isInternal('http://www.example.com:8080/joomla/index.php'),
+			'http://www.example.com:8080/joomla/index.php should NOT be internal'
+		);
+
+		self::setUpLocal('www.example.com', true, '/joomla/index.php', 'var=value 10');
+		$this->assertFalse(
+			JUri::isInternal('http://www.example.com:8080/joomla/index.php'),
+			'http://www.example.com:8080/joomla/index.php should NOT be internal'
+		);
 	}
 
 	/**