GHSA-72XP-P242-47P9 Symfony has a UrlGenerator Route-Requirement Bypass via Unanchored Regex Alternation → Off-Site //host URL Injection

Description Symfony routes can declare a requirements regex per path parameter, e.g. a route /locale/blog with requirements: locale: 'en|fr|de' . The Twig path / url helpers backed by UrlGenerator validate supplied parameter values against that regex before building the URL. UrlGenerator construc...