What happened
Twig is a template language for PHP. From version 1.0.0 to before version 3.27.0, SecurityPolicy::checkMethodAllowed() unconditionally whitelists all method calls on instances of Twig\Markup. Twig\Markup is not final, so subclasses inherit the bypass. An application that passes an object of a Markup-derived class into a sandboxed template (typically to mark a chunk of HTML as safe) inadvertently exposes every public method of that subclass to template authors, regardless of the configured allowedMethods list. This issue has been patched in version 3.27.0.
Affected versions
Twig: >= 1.0.0, < 3.27.0 Fixed: See vendor advisory.
Why it matters
Review the vendor advisory and exposure of the affected product to determine operational impact.
Detection & mitigation
- Apply vendor-provided updates or mitigations.
- Review affected product exposure and access logs.
Public PoC references
No public PoC reference has passed the current publication threshold.