diff --git a/src/Symfony/Bundle/FrameworkBundle/Command/ConfigDebugCommand.php b/src/Symfony/Bundle/FrameworkBundle/Command/ConfigDebugCommand.php
index 7d3373f3ebbf..4761b66ad901 100644
--- a/src/Symfony/Bundle/FrameworkBundle/Command/ConfigDebugCommand.php
+++ b/src/Symfony/Bundle/FrameworkBundle/Command/ConfigDebugCommand.php
@@ -11,12 +11,12 @@
 
 namespace Symfony\Bundle\FrameworkBundle\Command;
 
-use Symfony\Component\Config\Definition\Processor;
 use Symfony\Component\Console\Exception\LogicException;
 use Symfony\Component\Console\Input\InputArgument;
 use Symfony\Component\Console\Input\InputInterface;
 use Symfony\Component\Console\Output\OutputInterface;
 use Symfony\Component\Console\Style\SymfonyStyle;
+use Symfony\Component\DependencyInjection\Compiler\ValidateEnvPlaceholdersPass;
 use Symfony\Component\DependencyInjection\ContainerBuilder;
 use Symfony\Component\Yaml\Yaml;
 
@@ -80,15 +80,19 @@ protected function execute(InputInterface $input, OutputInterface $output)
         $container = $this->compileContainer();
 
         $extensionAlias = $extension->getAlias();
-        $configs = $container->getExtensionConfig($extensionAlias);
-        $configuration = $extension->getConfiguration($configs, $container);
-
-        $this->validateConfiguration($extension, $configuration);
+        $extensionConfig = [];
+        foreach ($container->getCompilerPassConfig()->getPasses() as $pass) {
+            if ($pass instanceof ValidateEnvPlaceholdersPass) {
+                $extensionConfig = $pass->getExtensionConfig();
+                break;
+            }
+        }
 
-        $configs = $container->resolveEnvPlaceholders($container->getParameterBag()->resolveValue($configs));
+        if (!isset($extensionConfig[$extensionAlias])) {
+            throw new \LogicException(sprintf('The extension with alias "%s" does not have configuration.', $extensionAlias));
+        }
 
-        $processor = new Processor();
-        $config = $container->resolveEnvPlaceholders($container->getParameterBag()->resolveValue($processor->processConfiguration($configuration, $configs)));
+        $config = $container->resolveEnvPlaceholders($extensionConfig[$extensionAlias]);
 
         if (null === $path = $input->getArgument('path')) {
             $io->title(
diff --git a/src/Symfony/Bundle/FrameworkBundle/Tests/Functional/ConfigDebugCommandTest.php b/src/Symfony/Bundle/FrameworkBundle/Tests/Functional/ConfigDebugCommandTest.php
index 2c0a75481b39..f52d48e89904 100644
--- a/src/Symfony/Bundle/FrameworkBundle/Tests/Functional/ConfigDebugCommandTest.php
+++ b/src/Symfony/Bundle/FrameworkBundle/Tests/Functional/ConfigDebugCommandTest.php
@@ -66,6 +66,14 @@ public function testDumpUndefinedBundleOption()
         $this->assertContains('Unable to find configuration for "test.foo"', $tester->getDisplay());
     }
 
+    public function testDumpWithPrefixedEnv()
+    {
+        $tester = $this->createCommandTester();
+        $tester->execute(['name' => 'FrameworkBundle']);
+
+        $this->assertContains("cookie_httponly: '%env(bool:COOKIE_HTTPONLY)%'", $tester->getDisplay());
+    }
+
     /**
      * @return CommandTester
      */
diff --git a/src/Symfony/Bundle/FrameworkBundle/Tests/Functional/app/ConfigDump/config.yml b/src/Symfony/Bundle/FrameworkBundle/Tests/Functional/app/ConfigDump/config.yml
index c1d128804605..432e35bd2f24 100644
--- a/src/Symfony/Bundle/FrameworkBundle/Tests/Functional/app/ConfigDump/config.yml
+++ b/src/Symfony/Bundle/FrameworkBundle/Tests/Functional/app/ConfigDump/config.yml
@@ -4,7 +4,10 @@ imports:
 framework:
     secret: '%secret%'
     default_locale: '%env(LOCALE)%'
+    session:
+        cookie_httponly: '%env(bool:COOKIE_HTTPONLY)%'
 
 parameters:
     env(LOCALE): en
+    env(COOKIE_HTTPONLY): '1'
     secret: test
diff --git a/src/Symfony/Component/DependencyInjection/Compiler/ValidateEnvPlaceholdersPass.php b/src/Symfony/Component/DependencyInjection/Compiler/ValidateEnvPlaceholdersPass.php
index 1848ec4dbcba..8fd84fac00ee 100644
--- a/src/Symfony/Component/DependencyInjection/Compiler/ValidateEnvPlaceholdersPass.php
+++ b/src/Symfony/Component/DependencyInjection/Compiler/ValidateEnvPlaceholdersPass.php
@@ -28,11 +28,15 @@ class ValidateEnvPlaceholdersPass implements CompilerPassInterface
 {
     private static $typeFixtures = ['array' => [], 'bool' => false, 'float' => 0.0, 'int' => 0, 'string' => ''];
 
+    private $extensionConfig = [];
+
     /**
      * {@inheritdoc}
      */
     public function process(ContainerBuilder $container)
     {
+        $this->extensionConfig = [];
+
         if (!class_exists(BaseNode::class) || !$extensions = $container->getExtensions()) {
             return;
         }
@@ -77,7 +81,7 @@ public function process(ContainerBuilder $container)
                 }
 
                 try {
-                    $processor->processConfiguration($configuration, $config);
+                    $this->extensionConfig[$name] = $processor->processConfiguration($configuration, $config);
                 } catch (TreeWithoutRootNodeException $e) {
                 }
             }
@@ -88,6 +92,18 @@ public function process(ContainerBuilder $container)
         $resolvingBag->clearUnusedEnvPlaceholders();
     }
 
+    /**
+     * @internal
+     */
+    public function getExtensionConfig(): array
+    {
+        try {
+            return $this->extensionConfig;
+        } finally {
+            $this->extensionConfig = [];
+        }
+    }
+
     private static function getType($value): string
     {
         switch ($type = \gettype($value)) {