CVE-2023-34252: Improper Control of Generation of Code ('Code Injection')
(updated )
Grav is a file-based Web platform. 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.
References
- github.com/advisories/GHSA-96xv-rmwj-6p9w
- github.com/getgrav/grav/blob/1.7.40/system/src/Grav/Common/Twig/Extension/GravExtension.php
- github.com/getgrav/grav/blob/1.7.40/system/src/Grav/Common/Utils.php
- github.com/getgrav/grav/commit/244758d4383034fe4cd292d41e477177870b65ec
- github.com/getgrav/grav/commit/71bbed12f950de8335006d7f91112263d8504f1b
- github.com/getgrav/grav/commit/8c2c1cb72611a399f13423fc6d0e1d998c03e5c8
- github.com/getgrav/grav/commit/9d01140a63c77075ef09b26ef57cf186138151a5
- github.com/getgrav/grav/security/advisories/GHSA-96xv-rmwj-6p9w
- nvd.nist.gov/vuln/detail/CVE-2023-34252
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