GHSA-MM6W-GR99-P3JJ
Vulnerability from github – Published: 2026-05-21 21:30 – Updated: 2026-05-21 21:30Description
The object-destructuring assignment syntax introduced in Twig 3.24.0 generates a call to CoreExtension::getAttribute() with the $sandboxed argument hardcoded to false, regardless of whether a SandboxExtension is active. This permanently disables the sandbox's property and method policy checks for every destructuring expression.
ObjectDestructuringSetBinary::compile() emits:
CoreExtension::getAttribute($this->env, $this->source, ..., \Twig\Template::ANY_CALL, false, false, false, ...);
// ^^^^^
// sandbox check never runs
Whereas GetAttrExpression::compile() correctly passes $env->hasExtension(SandboxExtension::class).
An attacker with write access to a sandboxed Twig template can read any public property or invoke any public getter on objects passed to the template engine, bypassing SecurityPolicy restrictions. The exploit requires only the {% do %} tag to be in allowedTags, which is a common configuration.
Resolution
The destructuring compiler now forwards the active sandbox flag to getAttribute() so property/method allowlists are enforced.
Credits
Twig would like to thank Anvil Secure in collaboration with Claude and Anthropic Research for reporting and fixing the issue.
{
"affected": [
{
"package": {
"ecosystem": "Packagist",
"name": "twig/twig"
},
"ranges": [
{
"events": [
{
"introduced": "3.24.0"
},
{
"fixed": "3.26.0"
}
],
"type": "ECOSYSTEM"
}
]
}
],
"aliases": [
"CVE-2026-46639"
],
"database_specific": {
"cwe_ids": [
"CWE-693"
],
"github_reviewed": true,
"github_reviewed_at": "2026-05-21T21:30:49Z",
"nvd_published_at": null,
"severity": "HIGH"
},
"details": "### Description\n\nThe object-destructuring assignment syntax introduced in Twig 3.24.0 generates a call to `CoreExtension::getAttribute()` with the `$sandboxed` argument hardcoded to `false`, regardless of whether a `SandboxExtension` is active. This permanently disables the sandbox\u0027s property and method policy checks for every destructuring expression.\n\n`ObjectDestructuringSetBinary::compile()` emits:\n\n```php\nCoreExtension::getAttribute($this-\u003eenv, $this-\u003esource, ..., \\Twig\\Template::ANY_CALL, false, false, false, ...);\n// ^^^^^\n// sandbox check never runs\n```\n\nWhereas `GetAttrExpression::compile()` correctly passes `$env-\u003ehasExtension(SandboxExtension::class)`.\n\nAn 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.\n\n### Resolution\n\nThe destructuring compiler now forwards the active sandbox flag to `getAttribute()` so property/method allowlists are enforced.\n\n### Credits\n\nTwig would like to thank Anvil Secure in collaboration with Claude and Anthropic Research for reporting and fixing the issue.",
"id": "GHSA-mm6w-gr99-p3jj",
"modified": "2026-05-21T21:30:49Z",
"published": "2026-05-21T21:30:49Z",
"references": [
{
"type": "WEB",
"url": "https://github.com/twigphp/Twig/security/advisories/GHSA-mm6w-gr99-p3jj"
},
{
"type": "WEB",
"url": "https://github.com/FriendsOfPHP/security-advisories/blob/master/twig/twig/CVE-2026-46639.yaml"
},
{
"type": "PACKAGE",
"url": "https://github.com/twigphp/Twig"
},
{
"type": "WEB",
"url": "https://symfony.com/cve-2026-46639"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N",
"type": "CVSS_V4"
}
],
"summary": "Twig: Sandbox property and method bypass via object-destructuring assignment"
}
Sightings
| Author | Source | Type | Date | Other |
|---|
Nomenclature
- Seen: The vulnerability was mentioned, discussed, or observed by the user.
- Confirmed: The vulnerability has been validated from an analyst's perspective.
- Published Proof of Concept: A public proof of concept is available for this vulnerability.
- Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
- Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
- Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
- Not confirmed: The user expressed doubt about the validity of the vulnerability.
- Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
Browse all ATT&CK techniques and the vulnerabilities related to each.
Related by attack behaviour
Vulnerabilities whose description is nearest to this one in the vector space of the CIRCL/vulnerability-attack-technique-biencoder model. This is a similarity search over the bi-encoder space (plain cosine), not a classification, and it has no measured accuracy.