diff --git a/src/Symfony/Bridge/PhpUnit/bin/simple-phpunit b/src/Symfony/Bridge/PhpUnit/bin/simple-phpunit
index bcfc432f8a..9b149cd78c 100755
--- a/src/Symfony/Bridge/PhpUnit/bin/simple-phpunit
+++ b/src/Symfony/Bridge/PhpUnit/bin/simple-phpunit
@@ -63,7 +63,7 @@ if (!file_exists("$PHPUNIT_DIR/phpunit-$PHPUNIT_VERSION/phpunit") || md5_file(__
     if (file_exists("phpunit-$PHPUNIT_VERSION")) {
         passthru(sprintf('\\' === DIRECTORY_SEPARATOR ? '(del /S /F /Q %s & rmdir %1$s) >nul': 'rm -rf %s', "phpunit-$PHPUNIT_VERSION"));
     }
-    if (extension_loaded('openssl') && ini_get('allow_url_fopen') && !isset($_SERVER['http_proxy']) && !isset($_SERVER['https_proxy'])) {
+    if (extension_loaded('openssl') && filter_var(ini_get('allow_url_fopen'), FILTER_VALIDATE_BOOLEAN) && !isset($_SERVER['http_proxy']) && !isset($_SERVER['https_proxy'])) {
         $remoteZip = "https://github.com/sebastianbergmann/phpunit/archive/$PHPUNIT_VERSION.zip";
         $remoteZipStream = @fopen($remoteZip, 'rb');
         if (!$remoteZipStream) {
@@ -214,7 +214,7 @@ if ($components) {
             // STATUS_STACK_BUFFER_OVERRUN (-1073740791/0xC0000409)
             // STATUS_ACCESS_VIOLATION (-1073741819/0xC0000005)
             // STATUS_HEAP_CORRUPTION (-1073740940/0xC0000374)
-            if ($procStatus && ('\\' !== DIRECTORY_SEPARATOR || !extension_loaded('apcu') || !ini_get('apc.enable_cli') || !in_array($procStatus, array(-1073740791, -1073741819, -1073740940)))) {
+            if ($procStatus && ('\\' !== DIRECTORY_SEPARATOR || !extension_loaded('apcu') || !filter_var(ini_get('apc.enable_cli'), FILTER_VALIDATE_BOOLEAN) || !in_array($procStatus, array(-1073740791, -1073741819, -1073740940)))) {
                 $exit = $procStatus;
                 echo "\033[41mKO\033[0m $component\n\n";
             } else {
diff --git a/src/Symfony/Bundle/FrameworkBundle/Command/AboutCommand.php b/src/Symfony/Bundle/FrameworkBundle/Command/AboutCommand.php
index 05b323070a..c7016c4ba3 100644
--- a/src/Symfony/Bundle/FrameworkBundle/Command/AboutCommand.php
+++ b/src/Symfony/Bundle/FrameworkBundle/Command/AboutCommand.php
@@ -84,8 +84,8 @@ EOT
             array('Architecture', (PHP_INT_SIZE * 8).' bits'),
             array('Intl locale', class_exists('Locale', false) && \Locale::getDefault() ? \Locale::getDefault() : 'n/a'),
             array('Timezone', date_default_timezone_get().' (<comment>'.(new \DateTime())->format(\DateTime::W3C).'</>)'),
-            array('OPcache', \extension_loaded('Zend OPcache') && ini_get('opcache.enable') ? 'true' : 'false'),
-            array('APCu', \extension_loaded('apcu') && ini_get('apc.enabled') ? 'true' : 'false'),
+            array('OPcache', \extension_loaded('Zend OPcache') && filter_var(ini_get('opcache.enable'), FILTER_VALIDATE_BOOLEAN) ? 'true' : 'false'),
+            array('APCu', \extension_loaded('apcu') && filter_var(ini_get('apc.enabled'), FILTER_VALIDATE_BOOLEAN) ? 'true' : 'false'),
             array('Xdebug', \extension_loaded('xdebug') ? 'true' : 'false'),
         );
 
diff --git a/src/Symfony/Component/Cache/Adapter/AbstractAdapter.php b/src/Symfony/Component/Cache/Adapter/AbstractAdapter.php
index 7b7336f278..6ea4ce7acb 100644
--- a/src/Symfony/Component/Cache/Adapter/AbstractAdapter.php
+++ b/src/Symfony/Component/Cache/Adapter/AbstractAdapter.php
@@ -117,7 +117,7 @@ abstract class AbstractAdapter implements AdapterInterface, LoggerAwareInterface
         }
 
         $apcu = new ApcuAdapter($namespace, (int) $defaultLifetime / 5, $version);
-        if ('cli' === \PHP_SAPI && !ini_get('apc.enable_cli')) {
+        if ('cli' === \PHP_SAPI && !filter_var(ini_get('apc.enable_cli'), FILTER_VALIDATE_BOOLEAN)) {
             $apcu->setLogger(new NullLogger());
         } elseif (null !== $logger) {
             $apcu->setLogger($logger);
diff --git a/src/Symfony/Component/Cache/Adapter/PhpArrayAdapter.php b/src/Symfony/Component/Cache/Adapter/PhpArrayAdapter.php
index 87c8090b91..4bd0da8c43 100644
--- a/src/Symfony/Component/Cache/Adapter/PhpArrayAdapter.php
+++ b/src/Symfony/Component/Cache/Adapter/PhpArrayAdapter.php
@@ -40,7 +40,7 @@ class PhpArrayAdapter implements AdapterInterface, PruneableInterface, Resettabl
     {
         $this->file = $file;
         $this->pool = $fallbackPool;
-        $this->zendDetectUnicode = ini_get('zend.detect_unicode');
+        $this->zendDetectUnicode = filter_var(ini_get('zend.detect_unicode'), FILTER_VALIDATE_BOOLEAN);
         $this->createCacheItem = \Closure::bind(
             function ($key, $value, $isHit) {
                 $item = new CacheItem();
@@ -68,7 +68,7 @@ class PhpArrayAdapter implements AdapterInterface, PruneableInterface, Resettabl
     public static function create($file, CacheItemPoolInterface $fallbackPool)
     {
         // Shared memory is available in PHP 7.0+ with OPCache enabled and in HHVM
-        if ((\PHP_VERSION_ID >= 70000 && ini_get('opcache.enable')) || \defined('HHVM_VERSION')) {
+        if ((\PHP_VERSION_ID >= 70000 && filter_var(ini_get('opcache.enable'), FILTER_VALIDATE_BOOLEAN)) || \defined('HHVM_VERSION')) {
             if (!$fallbackPool instanceof AdapterInterface) {
                 $fallbackPool = new ProxyAdapter($fallbackPool);
             }
diff --git a/src/Symfony/Component/Cache/Adapter/PhpFilesAdapter.php b/src/Symfony/Component/Cache/Adapter/PhpFilesAdapter.php
index 528d9c01fb..9ab870534f 100644
--- a/src/Symfony/Component/Cache/Adapter/PhpFilesAdapter.php
+++ b/src/Symfony/Component/Cache/Adapter/PhpFilesAdapter.php
@@ -36,6 +36,6 @@ class PhpFilesAdapter extends AbstractAdapter implements PruneableInterface
 
         $e = new \Exception();
         $this->includeHandler = function () use ($e) { throw $e; };
-        $this->zendDetectUnicode = ini_get('zend.detect_unicode');
+        $this->zendDetectUnicode = filter_var(ini_get('zend.detect_unicode'), FILTER_VALIDATE_BOOLEAN);
     }
 }
diff --git a/src/Symfony/Component/Cache/Simple/PhpArrayCache.php b/src/Symfony/Component/Cache/Simple/PhpArrayCache.php
index d7d87c019b..728d2bd7e5 100644
--- a/src/Symfony/Component/Cache/Simple/PhpArrayCache.php
+++ b/src/Symfony/Component/Cache/Simple/PhpArrayCache.php
@@ -36,7 +36,7 @@ class PhpArrayCache implements CacheInterface, PruneableInterface, ResettableInt
     {
         $this->file = $file;
         $this->pool = $fallbackPool;
-        $this->zendDetectUnicode = ini_get('zend.detect_unicode');
+        $this->zendDetectUnicode = filter_var(ini_get('zend.detect_unicode'), FILTER_VALIDATE_BOOLEAN);
     }
 
     /**
@@ -51,7 +51,7 @@ class PhpArrayCache implements CacheInterface, PruneableInterface, ResettableInt
     public static function create($file, CacheInterface $fallbackPool)
     {
         // Shared memory is available in PHP 7.0+ with OPCache enabled and in HHVM
-        if ((\PHP_VERSION_ID >= 70000 && ini_get('opcache.enable')) || \defined('HHVM_VERSION')) {
+        if ((\PHP_VERSION_ID >= 70000 && filter_var(ini_get('opcache.enable'), FILTER_VALIDATE_BOOLEAN)) || \defined('HHVM_VERSION')) {
             return new static($file, $fallbackPool);
         }
 
diff --git a/src/Symfony/Component/Cache/Simple/PhpFilesCache.php b/src/Symfony/Component/Cache/Simple/PhpFilesCache.php
index 9231c8cd39..9587f17bed 100644
--- a/src/Symfony/Component/Cache/Simple/PhpFilesCache.php
+++ b/src/Symfony/Component/Cache/Simple/PhpFilesCache.php
@@ -36,6 +36,6 @@ class PhpFilesCache extends AbstractCache implements PruneableInterface
 
         $e = new \Exception();
         $this->includeHandler = function () use ($e) { throw $e; };
-        $this->zendDetectUnicode = ini_get('zend.detect_unicode');
+        $this->zendDetectUnicode = filter_var(ini_get('zend.detect_unicode'), FILTER_VALIDATE_BOOLEAN);
     }
 }
diff --git a/src/Symfony/Component/Cache/Tests/Adapter/ApcuAdapterTest.php b/src/Symfony/Component/Cache/Tests/Adapter/ApcuAdapterTest.php
index 2b3c6b4432..a17b42bce4 100644
--- a/src/Symfony/Component/Cache/Tests/Adapter/ApcuAdapterTest.php
+++ b/src/Symfony/Component/Cache/Tests/Adapter/ApcuAdapterTest.php
@@ -24,10 +24,10 @@ class ApcuAdapterTest extends AdapterTestCase
 
     public function createCachePool($defaultLifetime = 0)
     {
-        if (!\function_exists('apcu_fetch') || !ini_get('apc.enabled')) {
+        if (!\function_exists('apcu_fetch') || !filter_var(ini_get('apc.enabled'), FILTER_VALIDATE_BOOLEAN)) {
             $this->markTestSkipped('APCu extension is required.');
         }
-        if ('cli' === \PHP_SAPI && !ini_get('apc.enable_cli')) {
+        if ('cli' === \PHP_SAPI && !filter_var(ini_get('apc.enable_cli'), FILTER_VALIDATE_BOOLEAN)) {
             if ('testWithCliSapi' !== $this->getName()) {
                 $this->markTestSkipped('apc.enable_cli=1 is required.');
             }
diff --git a/src/Symfony/Component/Cache/Tests/Adapter/MemcachedAdapterTest.php b/src/Symfony/Component/Cache/Tests/Adapter/MemcachedAdapterTest.php
index d1f8790340..59d28a33c1 100644
--- a/src/Symfony/Component/Cache/Tests/Adapter/MemcachedAdapterTest.php
+++ b/src/Symfony/Component/Cache/Tests/Adapter/MemcachedAdapterTest.php
@@ -137,7 +137,7 @@ class MemcachedAdapterTest extends AdapterTestCase
             'localhost',
             11222,
         );
-        if (ini_get('memcached.use_sasl')) {
+        if (filter_var(ini_get('memcached.use_sasl'), FILTER_VALIDATE_BOOLEAN)) {
             yield array(
                 'memcached://user:password@127.0.0.1?weight=50',
                 '127.0.0.1',
@@ -154,7 +154,7 @@ class MemcachedAdapterTest extends AdapterTestCase
             '/var/local/run/memcached.socket',
             0,
         );
-        if (ini_get('memcached.use_sasl')) {
+        if (filter_var(ini_get('memcached.use_sasl'), FILTER_VALIDATE_BOOLEAN)) {
             yield array(
                 'memcached://user:password@/var/local/run/memcached.socket?weight=25',
                 '/var/local/run/memcached.socket',
diff --git a/src/Symfony/Component/Cache/Tests/Simple/ApcuCacheTest.php b/src/Symfony/Component/Cache/Tests/Simple/ApcuCacheTest.php
index 737ed4e99d..3df32c1c5e 100644
--- a/src/Symfony/Component/Cache/Tests/Simple/ApcuCacheTest.php
+++ b/src/Symfony/Component/Cache/Tests/Simple/ApcuCacheTest.php
@@ -23,7 +23,7 @@ class ApcuCacheTest extends CacheTestCase
 
     public function createSimpleCache($defaultLifetime = 0)
     {
-        if (!\function_exists('apcu_fetch') || !ini_get('apc.enabled') || ('cli' === \PHP_SAPI && !ini_get('apc.enable_cli'))) {
+        if (!\function_exists('apcu_fetch') || !filter_var(ini_get('apc.enabled'), FILTER_VALIDATE_BOOLEAN) || ('cli' === \PHP_SAPI && !filter_var(ini_get('apc.enable_cli'), FILTER_VALIDATE_BOOLEAN))) {
             $this->markTestSkipped('APCu extension is required.');
         }
         if ('\\' === \DIRECTORY_SEPARATOR) {
diff --git a/src/Symfony/Component/Cache/Tests/Simple/MemcachedCacheTest.php b/src/Symfony/Component/Cache/Tests/Simple/MemcachedCacheTest.php
index b46d7e443d..ee9e49d3dd 100644
--- a/src/Symfony/Component/Cache/Tests/Simple/MemcachedCacheTest.php
+++ b/src/Symfony/Component/Cache/Tests/Simple/MemcachedCacheTest.php
@@ -146,7 +146,7 @@ class MemcachedCacheTest extends CacheTestCase
             'localhost',
             11222,
         );
-        if (ini_get('memcached.use_sasl')) {
+        if (filter_var(ini_get('memcached.use_sasl'), FILTER_VALIDATE_BOOLEAN)) {
             yield array(
                 'memcached://user:password@127.0.0.1?weight=50',
                 '127.0.0.1',
@@ -163,7 +163,7 @@ class MemcachedCacheTest extends CacheTestCase
             '/var/local/run/memcached.socket',
             0,
         );
-        if (ini_get('memcached.use_sasl')) {
+        if (filter_var(ini_get('memcached.use_sasl'), FILTER_VALIDATE_BOOLEAN)) {
             yield array(
                 'memcached://user:password@/var/local/run/memcached.socket?weight=25',
                 '/var/local/run/memcached.socket',
diff --git a/src/Symfony/Component/Cache/Traits/ApcuTrait.php b/src/Symfony/Component/Cache/Traits/ApcuTrait.php
index 65122cd8b7..c40afdc924 100644
--- a/src/Symfony/Component/Cache/Traits/ApcuTrait.php
+++ b/src/Symfony/Component/Cache/Traits/ApcuTrait.php
@@ -23,7 +23,7 @@ trait ApcuTrait
 {
     public static function isSupported()
     {
-        return \function_exists('apcu_fetch') && ini_get('apc.enabled');
+        return \function_exists('apcu_fetch') && filter_var(ini_get('apc.enabled'), FILTER_VALIDATE_BOOLEAN);
     }
 
     private function init($namespace, $defaultLifetime, $version)
@@ -75,7 +75,7 @@ trait ApcuTrait
      */
     protected function doClear($namespace)
     {
-        return isset($namespace[0]) && class_exists('APCuIterator', false) && ('cli' !== \PHP_SAPI || ini_get('apc.enable_cli'))
+        return isset($namespace[0]) && class_exists('APCuIterator', false) && ('cli' !== \PHP_SAPI || filter_var(ini_get('apc.enable_cli'), FILTER_VALIDATE_BOOLEAN))
             ? apcu_delete(new \APCuIterator(sprintf('/^%s/', preg_quote($namespace, '/')), APC_ITER_KEY))
             : apcu_clear_cache();
     }
diff --git a/src/Symfony/Component/Cache/Traits/PhpFilesTrait.php b/src/Symfony/Component/Cache/Traits/PhpFilesTrait.php
index 7728d17c53..b15ae8fce7 100644
--- a/src/Symfony/Component/Cache/Traits/PhpFilesTrait.php
+++ b/src/Symfony/Component/Cache/Traits/PhpFilesTrait.php
@@ -30,7 +30,7 @@ trait PhpFilesTrait
 
     public static function isSupported()
     {
-        return \function_exists('opcache_invalidate') && ini_get('opcache.enable');
+        return \function_exists('opcache_invalidate') && filter_var(ini_get('opcache.enable'), FILTER_VALIDATE_BOOLEAN);
     }
 
     /**
@@ -40,7 +40,7 @@ trait PhpFilesTrait
     {
         $time = time();
         $pruned = true;
-        $allowCompile = 'cli' !== \PHP_SAPI || ini_get('opcache.enable_cli');
+        $allowCompile = 'cli' !== \PHP_SAPI || filter_var(ini_get('opcache.enable_cli'), FILTER_VALIDATE_BOOLEAN);
 
         set_error_handler($this->includeHandler);
         try {
@@ -119,7 +119,7 @@ trait PhpFilesTrait
     {
         $ok = true;
         $data = array($lifetime ? time() + $lifetime : PHP_INT_MAX, '');
-        $allowCompile = 'cli' !== \PHP_SAPI || ini_get('opcache.enable_cli');
+        $allowCompile = 'cli' !== \PHP_SAPI || filter_var(ini_get('opcache.enable_cli'), FILTER_VALIDATE_BOOLEAN);
 
         foreach ($values as $key => $value) {
             if (null === $value || \is_object($value)) {
diff --git a/src/Symfony/Component/HttpFoundation/Session/Storage/Handler/AbstractSessionHandler.php b/src/Symfony/Component/HttpFoundation/Session/Storage/Handler/AbstractSessionHandler.php
index 5b5c1d8170..0d119498d0 100644
--- a/src/Symfony/Component/HttpFoundation/Session/Storage/Handler/AbstractSessionHandler.php
+++ b/src/Symfony/Component/HttpFoundation/Session/Storage/Handler/AbstractSessionHandler.php
@@ -131,7 +131,7 @@ abstract class AbstractSessionHandler implements \SessionHandlerInterface, \Sess
         if (\PHP_VERSION_ID < 70000) {
             $this->prefetchData = null;
         }
-        if (!headers_sent() && ini_get('session.use_cookies')) {
+        if (!headers_sent() && filter_var(ini_get('session.use_cookies'), FILTER_VALIDATE_BOOLEAN)) {
             if (!$this->sessionName) {
                 throw new \LogicException(sprintf('Session name cannot be empty, did you forget to call "parent::open()" in "%s"?.', \get_class($this)));
             }
@@ -159,7 +159,7 @@ abstract class AbstractSessionHandler implements \SessionHandlerInterface, \Sess
                     header($h, false);
                 }
             } else {
-                setcookie($this->sessionName, '', 0, ini_get('session.cookie_path'), ini_get('session.cookie_domain'), ini_get('session.cookie_secure'), ini_get('session.cookie_httponly'));
+                setcookie($this->sessionName, '', 0, ini_get('session.cookie_path'), ini_get('session.cookie_domain'), filter_var(ini_get('session.cookie_secure'), FILTER_VALIDATE_BOOLEAN), filter_var(ini_get('session.cookie_httponly'), FILTER_VALIDATE_BOOLEAN));
             }
         }
 
diff --git a/src/Symfony/Component/HttpFoundation/Session/Storage/Handler/PdoSessionHandler.php b/src/Symfony/Component/HttpFoundation/Session/Storage/Handler/PdoSessionHandler.php
index c5f0527f9c..8c0c42fd23 100644
--- a/src/Symfony/Component/HttpFoundation/Session/Storage/Handler/PdoSessionHandler.php
+++ b/src/Symfony/Component/HttpFoundation/Session/Storage/Handler/PdoSessionHandler.php
@@ -637,7 +637,7 @@ class PdoSessionHandler extends AbstractSessionHandler
                 throw new \RuntimeException('Failed to read session: INSERT reported a duplicate id but next SELECT did not return any data.');
             }
 
-            if (!ini_get('session.use_strict_mode') && self::LOCK_TRANSACTIONAL === $this->lockMode && 'sqlite' !== $this->driver) {
+            if (!filter_var(ini_get('session.use_strict_mode'), FILTER_VALIDATE_BOOLEAN) && self::LOCK_TRANSACTIONAL === $this->lockMode && 'sqlite' !== $this->driver) {
                 // In strict mode, session fixation is not possible: new sessions always start with a unique
                 // random id, so that concurrency is not possible and this code path can be skipped.
                 // Exclusive-reading of non-existent rows does not block, so we need to do an insert to block
diff --git a/src/Symfony/Component/HttpFoundation/Session/Storage/NativeSessionStorage.php b/src/Symfony/Component/HttpFoundation/Session/Storage/NativeSessionStorage.php
index 1ec5c7ff4e..a18f812d57 100644
--- a/src/Symfony/Component/HttpFoundation/Session/Storage/NativeSessionStorage.php
+++ b/src/Symfony/Component/HttpFoundation/Session/Storage/NativeSessionStorage.php
@@ -137,7 +137,7 @@ class NativeSessionStorage implements SessionStorageInterface
             throw new \RuntimeException('Failed to start the session: already started by PHP.');
         }
 
-        if (ini_get('session.use_cookies') && headers_sent($file, $line)) {
+        if (filter_var(ini_get('session.use_cookies'), FILTER_VALIDATE_BOOLEAN) && headers_sent($file, $line)) {
             throw new \RuntimeException(sprintf('Failed to start the session because headers have already been sent by "%s" at line %d.', $file, $line));
         }
 
diff --git a/src/Symfony/Component/HttpFoundation/Tests/Fixtures/response-functional/common.inc b/src/Symfony/Component/HttpFoundation/Tests/Fixtures/response-functional/common.inc
index f9c40a9a3c..0bdf9e4b75 100644
--- a/src/Symfony/Component/HttpFoundation/Tests/Fixtures/response-functional/common.inc
+++ b/src/Symfony/Component/HttpFoundation/Tests/Fixtures/response-functional/common.inc
@@ -22,7 +22,7 @@ error_reporting(-1);
 ini_set('html_errors', 0);
 ini_set('display_errors', 1);
 
-if (ini_get('xdebug.default_enable')) {
+if (filter_var(ini_get('xdebug.default_enable'), FILTER_VALIDATE_BOOLEAN)) {
     xdebug_disable();
 }
 
diff --git a/src/Symfony/Component/HttpFoundation/Tests/Session/Storage/Handler/PdoSessionHandlerTest.php b/src/Symfony/Component/HttpFoundation/Tests/Session/Storage/Handler/PdoSessionHandlerTest.php
index 3060452e9e..853e96d281 100644
--- a/src/Symfony/Component/HttpFoundation/Tests/Session/Storage/Handler/PdoSessionHandlerTest.php
+++ b/src/Symfony/Component/HttpFoundation/Tests/Session/Storage/Handler/PdoSessionHandlerTest.php
@@ -160,7 +160,7 @@ class PdoSessionHandlerTest extends TestCase
         if (\defined('HHVM_VERSION')) {
             $this->markTestSkipped('PHPUnit_MockObject cannot mock the PDOStatement class on HHVM. See https://github.com/sebastianbergmann/phpunit-mock-objects/pull/289');
         }
-        if (ini_get('session.use_strict_mode')) {
+        if (filter_var(ini_get('session.use_strict_mode'), FILTER_VALIDATE_BOOLEAN)) {
             $this->markTestSkipped('Strict mode needs no locking for new sessions.');
         }
 
diff --git a/src/Symfony/Component/PropertyAccess/PropertyAccessor.php b/src/Symfony/Component/PropertyAccess/PropertyAccessor.php
index 33763a73c8..bc76ea25ca 100644
--- a/src/Symfony/Component/PropertyAccess/PropertyAccessor.php
+++ b/src/Symfony/Component/PropertyAccess/PropertyAccessor.php
@@ -910,7 +910,7 @@ class PropertyAccessor implements PropertyAccessorInterface
         }
 
         $apcu = new ApcuAdapter($namespace, $defaultLifetime / 5, $version);
-        if ('cli' === \PHP_SAPI && !ini_get('apc.enable_cli')) {
+        if ('cli' === \PHP_SAPI && !filter_var(ini_get('apc.enable_cli'), FILTER_VALIDATE_BOOLEAN)) {
             $apcu->setLogger(new NullLogger());
         } elseif (null !== $logger) {
             $apcu->setLogger($logger);