Twig: Sandbox property and method bypass via object-destructuring assignment
Date: 2026-05
Affected: composer/twig/twig
Attack vector: other
Category: vulnerability-disclosure
Severity: High
CVE: CVE-2026-46639
CWE: CWE-693

### 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.


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Architectural layers (MAESTRO):