Grav Server Side Template Injection (SSTI) vulnerability

Exploitation

No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.

CVSS

9.1 · CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:C/C:H/I:H/A:H

EPSS

• CVE-2023-34251: 2.34% estimated exploitation activity in the next 30 days; percentile 83.62 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.

As published by the source; long descriptions are shortened.

Summary I found an RCE(Remote Code Execution) by SSTI in the admin screen. Details Remote Code Execution is possible by embedding malicious PHP code on the administrator screen by a user with page editing privileges. PoC 1. Log in to the administrator screen and access the edit screen of the default page "Typography". (http://127.0.0.1:8000/admin/pages/typography) 2. Open the browser's console screen and execute the following JavaScript code to confirm that an arbitrary command (id) is being executed. Execution Result - Payload: {{['id']|map('system')|join}} - Payload: {{['cat /etc/passwd']|map('system')|join}} PoC Video - PoC Video Impact Remote Command Execution (RCE) is possible. Occurrences - https://github.com/getgrav/grav/blob/develop/system/src/Grav/Common/Twig/Extension/GravExtension.php#L174 References - PortSwigger: Server-side template injection - HackTricks: SSTI (Server Side Template Injection)

Published by the source

16 Jun 2023, 19:35 UTC

Last modified by the source

5 Nov 2023, 05:03 UTC

Source last checked

26 Oct 2026, 14:10 UTC

1. Revision 1 · created · 26 Oct 2026

   Published from ghsa record GHSA-f9jf-4cp4-4fq5

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# Patch Next advisory brief: CVE-2023-34251

Advisory: Grav Server Side Template Injection (SSTI) vulnerability
IDs: CVE-2023-34251, GHSA-f9jf-4cp4-4fq5
Record: https://patchnext.com/advisories/cve-2023-34251 (revision 1, source checked 26 Oct 2026, 14:10 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: Critical (CVSS 9.1)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: getgrav/grav 1.7.42. A vendor fix does not mean a deployment is fixed.

## Affected components
- Packagist getgrav/grav: affected < 1.7.42; fixed in 1.7.42

## Suggested inspection (read-only)
- Packagist getgrav/grav: check the installed version with your package manager.

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on getgrav/grav.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://github.com/advisories/GHSA-f9jf-4cp4-4fq5 (GitHub-reviewed advisory GHSA-f9jf-4cp4-4fq5 lists affected ranges: Packagist getgrav/grav >=0 <1.7.42)

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