CVE-2023-34252
Grav Server-side Template Injection via Insufficient Validation in filterFilter
- Published
- Updated
- Reserved
- Assigned by
- GitHub_M
Description
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.
Public exploit
An exploit or proof of concept is public: anyone can try it against an unpatched system. CISA's SSVC rates its exploitation: a proof of concept is public.
Timeline
ID reserved
By GitHub_M
- 14 days later
· 14 days later
Published
- 18 months later
· 18 months later
Record updated
Changes after publication (a new score, a public exploit, EPSS crossing 1, 10 or 50 %, leaving KEV) are kept since November 2026; earlier ones are not known.
Scores
| Scored by | CVSS | Score | Vector |
|---|---|---|---|
| GitHub_MCNA (assigner) | 3.1 | High8.8 | CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H |
| NVDNVD · Modified | 3.1 | High7.2 | CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:H |
- EPSS (exploitation in 30 days)
- 2.1% · top 18% of all CVEs (7 Nov 2026)
- CISA SSVC
- Exploitation: poc · Automatable: yes · Technical impact: total
The list uses the assigner's score when there is one, then CISA's, then NVD's: High 8.8.
Weakness
Affected products
Affected packages
From reviewed advisories of the GitHub Advisory Database.
- Packagistgetgrav/gravGHSA-96xv-rmwj-6p9w (opens in a new tab)
References (4)
- https://github.com/getgrav/grav/security/advisories/GHSA-96xv-rmwj-6p9w (opens in a new tab)x_refsource_CONFIRMx_transferred
- https://github.com/getgrav/grav/commit/244758d4383034fe4cd292d41e477177870b65ec (opens in a new tab)x_refsource_MISCx_transferred
- https://github.com/getgrav/grav/blob/1.7.40/system/src/Grav/Common/Twig/Extension/GravExtension.php#L1692-L1698 (opens in a new tab)x_refsource_MISCx_transferred
- https://github.com/getgrav/grav/blob/1.7.40/system/src/Grav/Common/Utils.php#L1956-L2074 (opens in a new tab)x_refsource_MISCx_transferred
Sources
The same CVE in the primary databases and aggregators, to check against.
- CVE.org record (opens in a new tab)
- CVE List JSON (GitHub) (opens in a new tab)
- NVD (opens in a new tab)
- FIRST EPSS (opens in a new tab)
- OSV.dev (opens in a new tab)
- GitHub Advisory GHSA-96xv-rmwj-6p9w (opens in a new tab)
- CIRCL Vulnerability-Lookup (opens in a new tab)
Badge for a README or a ticket
[](https://trackcve.app/cve/CVE-2023-34252)Record last updated .