Summary
Twig: {% sandbox %}{% include %} skips checkSecurity() on cached templates (incomplete fix for CVE-2024-45411)
Description
The fix for CVE-2024-45411 / GHSA-6j75-5wfj-gh66 added an explicit $loaded->unwrap()->checkSecurity() call in CoreExtension::include() so that a template already cached in Environment::$loadedTemplates is re-checked when included with sandboxed = true.
The deprecated but still functional {% sandbox %}{% include ... %}{% endsandbox %} tag path was not updated: it compiles to enableSandbox(); yield from $this->load(...)->unwrap()->yield(...); disableSandbox(); with no checkSecurity() re-invocation. If the included template was loaded once outside the sandbox in the same Environment instance, its constructor (and therefore its compiled checkSecurity() call) already ran while isSandboxed() was false, so the tags/filters/functions allowlist enforced by SecurityPolicy::checkSecurity() is never applied.
An attacker who can author the included template gains access to every filter, function and tag registered in the environment, regardless of the sandbox policy.
Resolution
The compiled output of {% sandbox %}{% include %} now calls checkSecurity() on the loaded template, matching the behaviour of CoreExtension::include() with sandboxed = true.
Credits
Twig would like to thank Claude Mythos Preview (via Project Glasswing) for reporting the issue and providing the fix.
Impact
Affected versions
Security releases
Kodem intelligence
Severity tells you how bad this could be in the worst case. It does not tell you whether you are exposed. Exploitability and impact are functions of runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A vulnerable package can sit in your dependency tree and never run.
Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter. Kodem's runtime-powered SCA identifies whether this CVE is reachable in your applications.
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Frequently Asked Questions
- What is CVE-2026-46638? CVE-2026-46638 is a medium-severity security vulnerability in twig/twig (composer), affecting versions < 3.26.0. It is fixed in 3.26.0.
- Which versions of twig/twig are affected by CVE-2026-46638? twig/twig (composer) versions < 3.26.0 is affected.
- Is there a fix for CVE-2026-46638? Yes. CVE-2026-46638 is fixed in 3.26.0. Upgrade to this version or later.
- Is CVE-2026-46638 exploitable, and should I be worried? Whether CVE-2026-46638 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
- What actually determines whether CVE-2026-46638 is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
- How do I fix CVE-2026-46638? Upgrade
twig/twigto 3.26.0 or later.