Description

Twig: Sandbox property allowlist bypass via the column filter (array_column on objects)

Description

The column filter passes its input straight to PHP's native array_column(). When the array elements are objects, array_column() reads $obj->$name (and $obj->$index) directly, including invoking __get/__isset. Because this property read happens entirely in PHP native code and never reaches CoreExtension::getAttribute(), SandboxExtension::checkPropertyAllowed() is never consulted.

An untrusted template author with column in their allowedFilters list can therefore read any public or magic property of any object reachable in the render context, regardless of the SecurityPolicy allowedProperties list. This is a variant of CVE-2024-51755 / GHSA-jjxq-ff2g-95vh that the ArrayAccess-focused fix did not cover.

Resolution

The column filter now routes object property reads through the sandbox-aware attribute accessor so the property allowlist is enforced.

Credits

Twig: would like to thank Claude Mythos Preview (via Project Glasswing) for reporting the issue and providing the fix.

Mitigation

Aliases

References