Twig: Sandbox property and method bypass via object-destructuring assignment

Exploitation

No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.

CVSS 4.0

8.7 · 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 · score source

EPSS

• CVE-2026-46639: 0.39% estimated exploitation activity in the next 30 days; percentile 33.68 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.

As published by the source; long descriptions are shortened.

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: 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…

Published by the source

21 May 2026, 21:30 UTC

Last modified by the source

21 May 2026, 21:30 UTC

Source last checked

26 Oct 2026, 14:40 UTC

1. Revision 1 · created · 26 Oct 2026

   Published from ghsa record GHSA-mm6w-gr99-p3jj

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# Patch Next advisory brief: CVE-2026-46639

Advisory: Twig: Sandbox property and method bypass via object-destructuring assignment
IDs: CVE-2026-46639, GHSA-mm6w-gr99-p3jj
Record: https://patchnext.com/advisories/cve-2026-46639 (revision 1, source checked 26 Oct 2026, 14:40 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: High (CVSS 8.7)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: twig/twig 3.26.0. A vendor fix does not mean a deployment is fixed.

## Affected components
- Packagist twig/twig: affected >= 3.24.0, < 3.26.0; fixed in 3.26.0

## Suggested inspection (read-only)
- Packagist twig/twig: check the installed version with your package manager.

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on twig/twig.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://github.com/advisories/GHSA-mm6w-gr99-p3jj (GitHub-reviewed advisory GHSA-mm6w-gr99-p3jj lists affected ranges: Packagist twig/twig >=3.24.0 <3.26.0)

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