GHSA-mm6w-gr99-p3jj
Twig: Sandbox property and method bypass via object-destructuring assignment
Packages
Details
As written in the advisory (Markdown source, shown as plain text).
### 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.
References
External links from the advisory. They lead to third-party sites.