Executive brief
Twig is a popular template engine for PHP used to generate web pages. A security flaw in its sandbox mode allows users who can edit templates to bypass security restrictions and access sensitive data or functions they should not be able to reach. This could lead to the unauthorized disclosure of information or the execution of unintended actions within the application.
Technical details
A vulnerability exists in Twig's object-destructuring assignment syntax where the compiler hardcodes the sandbox argument to 'false' when calling CoreExtension::getAttribute(). This bypasses the SecurityPolicy checks enforced by the SandboxExtension, even when the extension is active. An attacker with the ability to modify or provide a sandboxed Twig template (requiring only the '{% do %}' tag to be allowed) can exploit this to read any public property or call any public getter method on objects passed to the template. The root cause is located in ObjectDestructuringSetBinary::compile(), which fails to check if the environment has the SandboxExtension enabled. The issue is resolved in version 3.26.0 by correctly forwarding the active sandbox flag.
Affected products
- twigphp Twig >= 3.24.0, < 3.26.0
Timeline
- 2026-05-20: patched: Version 3.26.0 released
- 2026-05-20: advisory: GitHub Security Advisory GHSA-mm6w-gr99-p3jj published
- 2026-07-14: disclosed: CVE-2026-46639 published to NVD