Affected versions

Twig versions <3.11.2; >=3.12,<3.14.1 are affected by this security issue.

The issue has been fixed in Twig 3.11.2 and 3.14.1.
Note that Twig versions 1 and 2 are not maintained anymore and are vulnerable.

Description

In a sandbox, and attacker can access attributes of Array-like objects as they were not checked by the security policy.
They are now checked via the property policy and the __isset() method is now called after the security check.
This is a BC break.

Resolution

The sandbox mode now ensures access to array-like's properties is allowed.

The patch for this issue is available here for the 3.11.x branch, and here for the 3.x branch.

Credits

We would like to thank Jamie Schouten for reporting the issue and Nicolas Grekas for providing the fix.

Sponsor the Symfony project.