Grav Vulnerable to XSS via Taxonomy Field Values in Admin Panel

Exploitation

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

CVSS

5.4 · CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N

EPSS

• CVE-2026-42842: 0.18% estimated exploitation activity in the next 30 days; percentile 7.98 (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 A Stored Cross-Site Scripting (XSS) vulnerability exists in the Grav CMS Form plugin's select field template. Taxonomy tag and category values are rendered with the Twig |raw filter in the admin panel, bypassing the global autoescape protection. An editor-level user can inject arbitrary JavaScript that executes in any administrator's browser session when they view or edit any page in the admin panel. Additionally, Grav's built-in XSS detection (Security::detectXss()) can be bypassed by using payloads that close the <option/<select context and use unquoted event handlers - the onevents regex fails to match event handlers without quotes or trailing spaces before . Important - The vulnerability is in the Form plugin (select.html.twig), which is installed by default with Grav - The XSS is cross-page: a malicious taxonomy value on one page executes when an admin edits any page, because taxonomy options are rendered from a shared global pool - An editor can exploit this without any…

Published by the source

5 May 2026, 21:24 UTC

Last modified by the source

13 May 2026, 14:04 UTC

Source last checked

26 Oct 2026, 14:40 UTC

1. Revision 1 · created · 26 Oct 2026

   Published from ghsa record GHSA-c2q3-p4jr-c55f

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# Patch Next advisory brief: CVE-2026-42842

Advisory: Grav Vulnerable to XSS via Taxonomy Field Values in Admin Panel
IDs: CVE-2026-42842, GHSA-c2q3-p4jr-c55f
Record: https://patchnext.com/advisories/cve-2026-42842 (revision 1, source checked 26 Oct 2026, 14:40 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: Medium (CVSS 5.4)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: getgrav/grav 2.0.0-beta.2. A vendor fix does not mean a deployment is fixed.

## Affected components
- Packagist getgrav/grav: affected < 2.0.0-beta.2; fixed in 2.0.0-beta.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-c2q3-p4jr-c55f (GitHub-reviewed advisory GHSA-c2q3-p4jr-c55f lists affected ranges: Packagist getgrav/grav >=0 <2.0.0-beta.2)

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