{"id":"GHSA-529h-vh3j-85hq","summary":"Twig: Sandbox filter, tag and function allow-list bypass when sandbox state changes between renders for a cached `Template`","details":"### Description\n\nThe per-template filter, tag and function allow-list check is compiled into the `checkSecurity()` method of each `Template` subclass and was invoked once from the constructor, gated by `SandboxExtension::isSandboxed($source)`. `Template` instances are then cached on the `Environment` in `$loadedTemplates`, so the verdict computed at construction time was sticky for the rest of the process.\n\nAny later change of sandbox state on the same `Environment` left that cached verdict in place: toggling `SandboxExtension::enableSandbox()`/`disableSandbox()`, swapping the policy via `setSecurityPolicy()`, a `SourcePolicyInterface` decision flip, or simply having a parent, macro or included template pre-instantiated outside the sandbox before a sandboxed render reached it. In all of these cases, the filters, tags and functions used by the affected template kept running with the original (typically empty) check, bypassing the `SecurityPolicy` allow-list.\n\nMethod, property and `__toString` allow-lists are not affected: they are enforced at every call site at runtime through `SandboxExtension::checkMethodAllowed()`, `checkPropertyAllowed()` and `ensureToStringAllowed()`, which re-read the current state on every call.\n\nLong-lived workers (FrankenPHP, RoadRunner, Symfony Messenger consumers, FPM with hot autoloading) that share a single `Environment` between sandboxed and non-sandboxed renders are the most exposed: a single non-sandboxed render of a shared layout pre-warms its `Template` instance, after which any later sandboxed render that extends, uses, includes or imports from that layout silently skips the filter/tag/function allow-list for the pre-warmed instance.\n\n### Resolution\n\nThe allow-list check is no longer run from the constructor. `Template` gains a public `ensureSecurityChecked()` method that calls the compiled `checkSecurity()` only when `SandboxExtension::isSandboxed($source)` returns true for the current source, and it is invoked at every entry point that can reach a `Template` instance whose security has not yet been verified against the current state: `Template::yield()`, `Template::yieldBlock()` (on the resolved block template, which covers `extends`, `use`, traits and parent blocks), `Template::getParent()` (which evaluates user code when the parent name is dynamic) and `Template::getTemplateForMacro()` (on the resolved macro template).\n\nThe explicit `checkSecurity()` calls previously emitted by `IncludeNode` and `CoreExtension::include()` are removed: the included template's own `yield()` now re-runs the check against the current sandbox state. The compiled `checkSecurity()` body is a cheap walk over compile-time-static arrays, so the per-render cost is negligible. Old cached compiled PHP files keep working unchanged: the constructor-time call they still contain is idempotent.\n\n### Credits\n\nTwig would like to thank Fabien Potencier for reporting and fixing the issue.","aliases":["CVE-2026-49981"],"modified":"2026-08-24T00:37:01.658444245Z","published":"2026-07-01T18:55:49Z","database_specific":{"severity":"HIGH","github_reviewed":true,"github_reviewed_at":"2026-07-01T18:55:49Z","nvd_published_at":null,"cwe_ids":["CWE-693","CWE-863"]},"references":[{"type":"WEB","url":"https://github.com/twigphp/Twig/security/advisories/GHSA-529h-vh3j-85hq"},{"type":"PACKAGE","url":"https://github.com/twigphp/Twig"},{"type":"WEB","url":"https://github.com/twigphp/Twig/releases/tag/v3.27.0"}],"affected":[{"package":{"name":"twig/twig","ecosystem":"Packagist","purl":"pkg:composer/twig/twig"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"3.27.0"}]}],"versions":["1.3.0","1.4.0","1.5.0","1.5.1","1.6.0","1.6.1","1.6.2","1.6.3","1.6.4","1.6.5","v1.10.0","v1.10.1","v1.10.2","v1.10.3","v1.11.0","v1.11.1","v1.12.0","v1.12.0-RC1","v1.12.1","v1.12.2","v1.12.3","v1.13.0","v1.13.1","v1.13.2","v1.14.0","v1.14.1","v1.14.2","v1.15.0","v1.15.1","v1.16.0","v1.16.1","v1.16.2","v1.16.3","v1.17.0","v1.18.0","v1.18.1","v1.18.2","v1.19.0","v1.20.0","v1.21.0","v1.21.1","v1.21.2","v1.22.0","v1.22.1","v1.22.2","v1.22.3","v1.23.0","v1.23.1","v1.23.2","v1.23.3","v1.24.0","v1.24.1","v1.24.2","v1.25.0","v1.26.0","v1.26.1","v1.27.0","v1.28.0","v1.28.1","v1.28.2","v1.29.0","v1.30.0","v1.31.0","v1.32.0","v1.33.0","v1.33.1","v1.33.2","v1.34.0","v1.34.1","v1.34.2","v1.34.3","v1.34.4","v1.35.0","v1.35.1","v1.35.2","v1.35.3","v1.35.4","v1.36.0","v1.37.0","v1.37.1","v1.38.0","v1.38.1","v1.38.2","v1.38.3","v1.38.4","v1.39.0","v1.39.1","v1.40.0","v1.40.1","v1.41.0","v1.42.0","v1.42.1","v1.42.2","v1.42.3","v1.42.4","v1.42.5","v1.43.0","v1.43.1","v1.44.0","v1.44.1","v1.44.2","v1.44.3","v1.44.4","v1.44.5","v1.44.6","v1.44.7","v1.44.8","v1.7.0","v1.8.0","v1.8.1","v1.8.2","v1.8.3","v1.9.0","v1.9.1","v1.9.2","v2.0.0","v2.1.0","v2.10.0","v2.11.0","v2.11.1","v2.11.2","v2.11.3","v2.12.0","v2.12.1","v2.12.2","v2.12.3","v2.12.4","v2.12.5","v2.13.0","v2.13.1","v2.14.0","v2.14.1","v2.14.10","v2.14.11","v2.14.12","v2.14.13","v2.14.2","v2.14.3","v2.14.4","v2.14.5","v2.14.6","v2.14.7","v2.14.8","v2.14.9","v2.15.0","v2.15.1","v2.15.2","v2.15.3","v2.15.4","v2.15.5","v2.15.6","v2.16.0","v2.16.1","v2.2.0","v2.3.0","v2.3.1","v2.3.2","v2.4.0","v2.4.1","v2.4.2","v2.4.3","v2.4.4","v2.4.5","v2.4.6","v2.4.7","v2.4.8","v2.5.0","v2.6.0","v2.6.1","v2.6.2","v2.7.0","v2.7.1","v2.7.2","v2.7.3","v2.7.4","v2.8.0","v2.8.1","v2.9.0","v3.0.0","v3.0.0-BETA1","v3.0.1","v3.0.2","v3.0.3","v3.0.4","v3.0.5","v3.1.0","v3.1.1","v3.10.0","v3.10.1","v3.10.2","v3.10.3","v3.11.0","v3.11.1","v3.11.2","v3.11.3","v3.12.0","v3.13.0","v3.14.0","v3.14.1","v3.14.2","v3.15.0","v3.16.0","v3.17.0","v3.17.1","v3.18.0","v3.19.0","v3.2.1","v3.20.0","v3.21.0","v3.21.1","v3.22.0","v3.22.1","v3.22.2","v3.23.0","v3.24.0","v3.25.0","v3.26.0","v3.3.0","v3.3.1","v3.3.10","v3.3.2","v3.3.3","v3.3.4","v3.3.5","v3.3.6","v3.3.7","v3.3.8","v3.3.9","v3.4.0","v3.4.1","v3.4.2","v3.4.3","v3.5.0","v3.5.1","v3.6.0","v3.6.1","v3.7.0","v3.7.1","v3.8.0","v3.9.0","v3.9.1","v3.9.2","v3.9.3"],"database_specific":{"source":"https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2026/07/GHSA-529h-vh3j-85hq/GHSA-529h-vh3j-85hq.json","last_known_affected_version_range":"\u003c= 3.26.0"}}],"schema_version":"1.9.0","severity":[{"type":"CVSS_V4","score":"CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N"}]}