CVE-2026-46636

Twig's sandbox security policy unconditionally whitelists every method call on instances of Twig\Markup, and because Twig\Markup is not final, this blanket allowance is inherited by any subclass. The flaw is triggered when an application passes an object of a Markup-derived class into a sandboxed template, which is a common pattern for marking HTML chunks as safe; template authors can then call any public method of that subclass regardless of the configured allowedMethods list. An attacker who can influence template content in such an application could invoke otherwise-restricted public methods, and the CVSS 4.0 score of 8.7 indicates a high potential confidentiality impact with no integrity or availability impact. Any application running an affected Twig version (1.0.0 through before 3.27.0) that uses the sandbox extension together with Markup subclasses is exposed. There is currently no known public proof-of-concept, no CISA KEV listing, and a low EPSS exploitation probability of 0.4%, indicating no confirmed exploitation in the wild.

What to do: Upgrade Twig to version 3.27.0 or later, which fixes the checkMethodAllowed() bypass. If upgrading is not immediately possible, avoid passing objects of Twig\Markup-derived classes into sandboxed templates, or restrict template authors from invoking methods on those objects. Audit all uses of the sandbox extension (sandboxed templates, e.g. via includes or inline sandboxing) to identify Markup subclass inputs and confirm which public methods become reachable to template authors.