Grav: Authenticated ReDoS via regex_replace in Twig Sandbox

Exploitation

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

CVSS 4.0

6.0 · CVSS:4.0/AV:N/AC:H/AT:P/PR:L/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N · score source

EPSS

• CVE-2026-62237: 0.30% estimated exploitation activity in the next 30 days; percentile 22.87 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.
• CVE-2026-62672: 0.38% estimated exploitation activity in the next 30 days; percentile 32.21 (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 regexreplace filter and function are allowlisted in Grav's Twig content sandbox. When Twig processing in page content is enabled security.twigcontent.processenabled: true, authenticated page editors can supply a catastrophically backtracking PCRE pattern, causing unbounded CPU consumption and denying service to the entire web server process. --- Details The Twig sandbox allowlists, defined in system/config/security.yaml, explicitly include regexreplace in both the filter and function permission lists: Source: system/config/security.yaml The underlying implementation passes the caller-controlled $pattern directly into PHP's pregreplace() without any pattern complexity validation: Source: system/src/Grav/Common/Twig/Extension/GravExtension.php:1317-1319 When twigcontent.processenabled is true, page body content is sandboxed but can use any allowlisted filter. An editor who embeds a catastrophic backtracking pattern causes the PCRE engine to enter exponential time…

Published by the source

2 Sep 2026, 14:50 UTC

Last modified by the source

17 Sep 2026, 16:45 UTC

Source last checked

26 Oct 2026, 14:53 UTC

1. Revision 3 · amended · 26 Oct 2026

   Amended from ghsa record GHSA-37f3-6p89-6qr9

2. Revision 2 · amended · 25 Oct 2026

   Reviewed OSV alias/range/CVSS4 correction; package source scopes and original publication preserved. No customer finding resolved.

3. Revision 1 · created · 24 Oct 2026

   Published from osv record GHSA-37f3-6p89-6qr9

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# Patch Next advisory brief: CVE-2026-62237

Advisory: Grav: Authenticated ReDoS via regex_replace in Twig Sandbox
IDs: CVE-2026-62237, GHSA-37f3-6p89-6qr9
Record: https://patchnext.com/advisories/cve-2026-62237 (revision 3, source checked 26 Oct 2026, 14:53 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: Medium (CVSS 6.0)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: getgrav/grav 2.0.4. A vendor fix does not mean a deployment is fixed.

## Affected components
- Packagist getgrav/grav: affected < 2.0.4; fixed in 2.0.4

## 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://osv.dev/vulnerability/GHSA-37f3-6p89-6qr9 (OSV record GHSA-37f3-6p89-6qr9 lists affected ranges: Packagist getgrav/grav >=0 <2.0.4 (fixed))
- Verified: https://github.com/advisories/GHSA-37f3-6p89-6qr9 (GitHub-reviewed advisory GHSA-37f3-6p89-6qr9 lists affected ranges: Packagist getgrav/grav >=0 <2.0.4)

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