RCE in Getgrav Grav
CVE-2023-34252
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 · last modified .
CVSS v3 metric
CVSS v3 base score 8.8 (High). Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H.
EPSS exploit prediction
EPSS: 0.021 (80.7th percentile), scored .
Low probability of exploitation in the next 30 days, but still tracked. 81st percentile — 80.7% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.021 · newest: 0.021 · change: 0.000
Affected products
- Getgrav Grav — versions < 1.7.42
Weakness classification (CWE)
References
- github.com/getgrav/grav/security/advisories/GHSA-96xv-rmwj-6p9w (Exploit, Vendor Advisory)
- github.com/getgrav/grav/commit/244758d4383034fe4cd292d41e477177870b65ec (Patch)
- github.com/getgrav/grav/blob/1.7.40/system/src/Grav/Common/Twig/Extension/GravE… (Issue Tracking)
- github.com/getgrav/grav/blob/1.7.40/system/src/Grav/Common/Utils.php (Issue Tracking)
Frequently asked questions
- What is CVE-2023-34252?
- CVE-2023-34252 is a high-severity vulnerability in Getgrav Grav, classified under Incomplete List of Disallowed Inputs. CVSS score: 8.8/10. Published 2023-06-14.
- How severe is CVE-2023-34252?
- High severity. CVSS v3 base score is 8.8 out of 10.