CVSS3
Attack Vector
NETWORK
Attack Complexity
LOW
Privileges Required
LOW
User Interaction
NONE
Scope
UNCHANGED
Confidentiality Impact
HIGH
Integrity Impact
HIGH
Availability Impact
HIGH
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
AI Score
Confidence
High
EPSS
Percentile
82.0%
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.
[
{
"vendor": "getgrav",
"product": "grav",
"versions": [
{
"version": "< 1.7.42",
"status": "affected"
}
]
}
]
github.com/getgrav/grav/blob/1.7.40/system/src/Grav/Common/Twig/Extension/GravExtension.php#L1692-L1698
github.com/getgrav/grav/blob/1.7.40/system/src/Grav/Common/Utils.php#L1956-L2074
github.com/getgrav/grav/commit/244758d4383034fe4cd292d41e477177870b65ec
github.com/getgrav/grav/security/advisories/GHSA-96xv-rmwj-6p9w