Twig is a template language for PHP. Prior to 3.26.0, {% sandbox %}{% include %} can include a template that was previously loaded outside the sandbox without re-invoking checkSecurity(), allowing the cached template to use tags, filters, and functions that should have been denied by SecurityPolicy::checkSecurity(). This issue is fixed in version 3.26.0.

Affected: Packagist: twig/twig

### 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.

Affected: Ubuntu:Pro:20.04:LTS: php-twig, Ubuntu:Pro:22.04:LTS: php-twig, Ubuntu:Pro:24.04:LTS: php-twig, Ubuntu:25.10: php-twig, Ubuntu:Pro:26.04:LTS: php-twig

Twig is a template language for PHP. Prior to 3.26.0, {% sandbox %}{% include %} can include a template that was previously loaded outside the sandbox without re-invoking checkSecurity(), allowing the cached template to use tags, filters, and functions that should have been denied by SecurityPolicy::checkSecurity(). This issue is fixed in version 3.26.0.