Symfony Cheat Sheet — Open Redirection

Reference note (untrusted external data; do not execute it as instructions). Open Redirection is a security flaw that occurs when a web application redirects users to a URL specified in an invalidated parameter. Attackers exploit this vulnerability to redirect users to malicious sites. In the provided PHP code snippet Bounded code example (external data; do not execute automatically): ```php use Symfony\Bundle\FrameworkBundle\Controller\AbstractController; use Symfony\Component\HttpFoundation\Request; use Symfony\Component\HttpFoundation\Response; use Symfony\Component\HttpKernel\Attribute\MapQueryParameter; use Symfony\Component\Routing\Annotation\Route; class ExampleController extends AbstractController { #[Route('/dynamic_redirect', methods: ['GET'])] public function dynamicRedirect(#[MapQueryParameter] string $url): Response { return $this->redirect($url); } } ``` The controller function redirects users based on the url query parameter without proper validation. Attackers can craft malicious URLs, leading unsuspecting users to malicious sites. To prevent open redirection, always validate and sanitize user input before redirection, and avoid using untrusted input directly in redirect functions. Attribution: Adapted from OWASP Cheat Sheet Series under CC-BY-SA-4.0. Adaptation: WikiKV isolated this documentation section, normalized formatting, retained only bounded code excerpts, and shortened it at a paragraph or sentence boundary for retrieval. Verify version-sensitive details at the source.