Vulnerability · Published Jun 14, 2023 · Assigned by GitHub_M
CVE-2023-34252Grav Server-side Template Injection via Insufficient Validation in filterFilter
High 8.8
In plain English
A high-severity security flaw in grav from getgrav. Proof-of-concept exploit code is public. The chance it is exploited in the next 30 days is estimated at 2.1% (higher than 82% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.
Official 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.
Affected packages & fixed versions
| Ecosystem | Package | Fixed in | Advisory |
|---|---|---|---|
| Packagist | getgrav/grav | 1.7.42 | GHSA-96xv-rmwj-6p9w |
Affected products (as reported)
Weakness: CWE-184, CWE-1336 · Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
References
- https://github.com/getgrav/grav/security/advisories/GHSA-96xv-rmwj-6p9w x_refsource_CONFIRM
- https://github.com/getgrav/grav/commit/244758d4383034fe4cd292d41e477177870b65ec x_refsource_MISC
- https://github.com/getgrav/grav/blob/1.7.40/system/src/Grav/Common/Twig/Extension/GravExtension.php#L1692-L1698 x_refsource_MISC
- https://github.com/getgrav/grav/blob/1.7.40/system/src/Grav/Common/Utils.php#L1956-L2074 x_refsource_MISC