{"id":"CVE-2023-34252","aliases":["GHSA-96xv-rmwj-6p9w"],"url":"https://o3.security/vulnerability/CVE-2023-34252","summary":"Grav Server-side Template Injection via Insufficient Validation in filterFilter","details":"Grav is a flat-file content management system. Prior to version 1.7.42, there is a logic flaw in the `GravExtension.filterFilter()` function whereby validation against a denylist of unsafe functions is only performed when the argument passed to filter is a string. However, passing an array as a callable argument allows the validation check to be skipped. Consequently, a low privileged attacker with login access to Grav Admin panel and page creation/update permissions is able to inject malicious templates to obtain remote code execution. The vulnerability can be found in the `GravExtension.filterFilter()` function declared in `/system/src/Grav/Common/Twig/Extension/GravExtension.php`. Version 1.7.42 contains a patch for this issue. End users should also ensure that `twig.undefined_functions` and `twig.undefined_filters` properties in `/path/to/webroot/system/config/system.yaml` configuration file are set to `false` to disallow Twig from treating undefined filters/functions as PHP functions and executing them.","published":"2023-06-14T21:38:48.358Z","modified":"2026-08-12T03:51:32.894656310Z","cvss":{"score":8.8,"severity":"HIGH","vector":"CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H"},"epss":{"score":0.02074,"percentile":0.79747,"asOf":"2026-08-23"},"cisaKev":null,"exploitsKnown":1,"affectedPackages":[{"ecosystem":"Packagist","name":"getgrav/grav","fixedVersion":"1.7.42"}],"fix":{"url":"https://github.com/getgrav/grav/commit/244758d4383034fe4cd292d41e477177870b65ec","label":"getgrav/grav@244758d"},"references":[{"type":"WEB","url":"https://github.com/getgrav/grav/blob/1.7.40/system/src/Grav/Common/Twig/Extension/GravExtension.php#L1692-L1698"},{"type":"WEB","url":"https://github.com/getgrav/grav/blob/1.7.40/system/src/Grav/Common/Utils.php#L1956-L2074"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2023/34xxx/CVE-2023-34252.json"},{"type":"ADVISORY","url":"https://github.com/getgrav/grav/security/advisories/GHSA-96xv-rmwj-6p9w"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2023-34252"},{"type":"FIX","url":"https://github.com/getgrav/grav/commit/244758d4383034fe4cd292d41e477177870b65ec"}],"provenance":{"sources":["OSV.dev","FIRST.org (EPSS)"],"lastVerified":"2026-08-12T03:51:32.894656310Z"}}