grav Server-side Template Injection (SSTI) mitigation bypass

Exploitation

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

CVSS

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

EPSS

• CVE-2023-37897: 2.81% estimated exploitation activity in the next 30 days; percentile 86.53 (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 The fix for SSTI using |map, |filter and |reduce twigs implemented in the commit 71bbed1 introduces bypass of the denylist due to incorrect return value from isDangerousFunction(), which allows to execute the payload prepending double backslash (\\) Details The isDangerousFunction() check in version 1.7.42 and onwards retuns false value instead of true when the \ symbol is found in the $name. Based on the code where the function is used, it is expected that any dangerous condition would return true when |map('\system') is used in the malicious payload, the single backslash is dropped prior to reaching strpos($name, '\\') check, thus $name variable already has no backslash, and the command is blacklisted because it reaches the if (inarray($name, $commandExecutionFunctions)) { validation step. However if |map('\\system') is used (i.e. double backslash), then the strpos($name, "\\") !== false takes effect, and isDangerousFunction() returns false , in which case the RuntimeError…

Published by the source

19 Jul 2023, 22:11 UTC

Last modified by the source

10 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-9436-3gmp-4f53

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# Patch Next advisory brief: CVE-2023-37897

Advisory: grav Server-side Template Injection (SSTI) mitigation bypass
IDs: CVE-2023-37897, GHSA-9436-3gmp-4f53
Record: https://patchnext.com/advisories/cve-2023-37897 (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: High (CVSS 7.2)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: getgrav/grav 1.7.42.2. A vendor fix does not mean a deployment is fixed.

## Affected components
- Packagist getgrav/grav: affected <= 1.7.42.1; fixed in 1.7.42.2

## 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-9436-3gmp-4f53 (GitHub-reviewed advisory GHSA-9436-3gmp-4f53 lists affected ranges: Packagist getgrav/grav >=0 <=1.7.42.1)

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