CVE-2026-46639

Description

### Description The object-destructuring assignment syntax introduced in Twig 3.24.0 generates a call to `CoreExtension::getAttribute()` with the `$sandboxed` argument hardcoded to `false`, regardless of whether a `SandboxExtension` is active. This permanently disables the sandbox's property and method policy checks for every destructuring expression. `ObjectDestructuringSetBinary::compile()` emits: ```php CoreExtension::getAttribute($this->env, $this->source, ..., \Twig\Template::ANY_CALL, false, false, false, ...); // ^^^^^ // sandbox check never runs ``` Whereas `GetAttrExpression::compile()` correctly passes `$env->hasExtension(SandboxExtension::class)`. An attacker with write access to a sandboxed Twig template can read any public property or invoke any public getter on objects passed to the template engine, bypassing `SecurityPolicy` restrictions. The exploit requires only the `{% do %}` tag to be in `allowedTags`, which is a common configuration. ### Resolution The destructuring compiler now forwards the active sandbox flag to `getAttribute()` so property/method allowlists are enforced. ### Credits Twig would like to thank Anvil Secure in collaboration with Claude and Anthropic Research for reporting and fixing the issue.

How to fix CVE-2026-46639

To remediate CVE-2026-46639, upgrade the affected package to a fixed version below.

• —upgrade to 3.26.0-1 or later
• —upgrade to 3.26.0 or later

Is CVE-2026-46639 being exploited?

No exploitation signal available. Neither CISA KEV nor a current EPSS score has been published for CVE-2026-46639.

Affected packages (2)

• from 0, < 3.26.0-1
• >= 3.24.0, < 3.26.0

CVSS scores

References (5)

• ADVISORYsecurity-tracker.debian.org/tracker/CVE-2026-46639
• PATCHgithub.com/twigphp/Twig
• WEBgithub.com/FriendsOfPHP/security-advisories/blob/master/twig/twig/CVE-2026-46639.yaml
• WEBgithub.com/twigphp/Twig/security/advisories/GHSA-mm6w-gr99-p3jj