Grav up to 1.7.41 Template GravExtension.filterFilter incomplete blacklist

Summaryinfo

A vulnerability was found in Grav up to 1.7.41. It has been rated as critical. This impacts the function GravExtension.filterFilter of the component Template Handler. The manipulation leads to incomplete blacklist. This vulnerability is documented as CVE-2023-34252. The attack can be initiated remotely. There is not any exploit available. Upgrading the affected component is advised.

Detailsinfo

A vulnerability, which was classified as critical, has been found in Grav up to 1.7.41. This issue affects the function GravExtension.filterFilter of the component Template Handler. The manipulation with an unknown input leads to a incomplete blacklist vulnerability. Using CWE to declare the problem leads to CWE-184. The product implements a protection mechanism that relies on a list of inputs (or properties of inputs) that are not allowed by policy or otherwise require other action to neutralize before additional processing takes place, but the list is incomplete, leading to resultant weaknesses. Impacted is confidentiality, integrity, and availability. The summary by CVE is:

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.

The weakness was released 06/15/2023 as GHSA-96xv-rmwj-6p9w. The advisory is shared at github.com. The identification of this vulnerability is CVE-2023-34252 since 05/31/2023. Technical details are known, but no exploit is available. MITRE ATT&CK project uses the attack technique T1562.006 for this issue.

Upgrading to version 1.7.42 eliminates this vulnerability. Applying the patch 244758d4383034fe4cd292d41e477177870b65ec is able to eliminate this problem. The bugfix is ready for download at github.com. The best possible mitigation is suggested to be upgrading to the latest version.

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Productinfo

Name

• Grav

Version

• 1.7.0
• 1.7.1
• 1.7.2
• 1.7.3
• 1.7.4
• 1.7.5
• 1.7.6
• 1.7.7
• 1.7.8
• 1.7.9
• 1.7.10
• 1.7.11
• 1.7.12
• 1.7.13
• 1.7.14
• 1.7.15
• 1.7.16
• 1.7.17
• 1.7.18
• 1.7.19
• 1.7.20
• 1.7.21
• 1.7.22
• 1.7.23
• 1.7.24
• 1.7.25
• 1.7.26
• 1.7.27
• 1.7.28
• 1.7.29
• 1.7.30
• 1.7.31
• 1.7.32
• 1.7.33
• 1.7.34
• 1.7.35
• 1.7.36
• 1.7.37
• 1.7.38
• 1.7.39
• 1.7.40
• 1.7.41

License

• open-source

CPE 2.3info

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CPE 2.2info

• 🔍
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