CVE-2023-34252
Published: 14 June 2023
Summary
CVE-2023-34252 is a high-severity Incomplete List of Disallowed Inputs (CWE-184) vulnerability in Getgrav Grav. Its CVSS base score is 8.8 (High).
Operationally, ranked in the top 32.4% of CVEs by exploit likelihood; it is not currently listed in the CISA KEV catalog; a public proof-of-concept is referenced.
EU & UK References
- 🇪🇺 ENISA EUVD: EUVD-2023-1758
Vulnerability details
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.…
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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.
- CWE(s)
Related Threats
No named actor attribution yet. ATT&CK technique mapping in progress for this CVE.
Affected Assets
Mitigating Controls
Likely Mitigating Controls AI
Per-CVE control mapping for this CVE has not run yet; the list below is derived from the weakness types (CWEs) cited in the NVD entry.
Makes persistent code injection into loaded programs impossible when the executable image itself resides on hardware-protected read-only media.
Dynamically generated code can be produced and executed inside the isolated chamber, preventing host compromise from code-injection payloads.
Validates inputs used in dynamic code generation to block injected directives.
Directly prevents execution of attacker-supplied code written into data memory regions.
Spam filters rely on evolving blacklists, signatures, and heuristics of disallowed message patterns; keeping them updated per the control directly mitigates incomplete disallowed-input lists.