Kirby CMS's system API endpoint leaks installed version and license data to authenticated users

Exploitation

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

CVSS 4.0

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

EPSS

• CVE-2026-42051: 0.19% estimated exploitation activity in the next 30 days; percentile 9.03 (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.

TL;DR This vulnerability affects all Kirby sites that might have potential attackers in the group of authenticated Panel users. ---- Introduction Missing authorization allows authenticated users to perform actions they are not intended to have access to. The effects of missing authorization can include unauthorized access to sensitive information as well as unauthorized changes to content or system information. Impact Kirby's user permissions control which user role is allowed to perform specific actions in the CMS. These permissions are defined for each role in the user blueprint (site/blueprints/users/...). The permissions control the authorization of user actions (with handling of model-specific authorization omitted here for brevity). Kirby provides the access.system permission (among others) that controls access to the system area of the Kirby Panel. This area contains internal system information like the installed Kirby, plugin and server versions, security state and Kirby…

Published by the source

4 May 2026, 19:59 UTC

Last modified by the source

13 May 2026, 13:39 UTC

Source last checked

26 Oct 2026, 14:40 UTC

1. Revision 1 · created · 26 Oct 2026

   Published from ghsa record GHSA-x68m-c7jf-2572

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# Patch Next advisory brief: CVE-2026-42051

Advisory: Kirby CMS's system API endpoint leaks installed version and license data to authenticated users
IDs: CVE-2026-42051, GHSA-x68m-c7jf-2572
Record: https://patchnext.com/advisories/cve-2026-42051 (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 5.3)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: getkirby/cms 5.4.0, 4.9.0. A vendor fix does not mean a deployment is fixed.

## Affected components
- Packagist getkirby/cms: affected <= 4.8.0; >= 5.0.0, <= 5.3.3; fixed in 4.9.0, 5.4.0

## Suggested inspection (read-only)
- Packagist getkirby/cms: 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 getkirby/cms.
- 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-x68m-c7jf-2572 (GitHub-reviewed advisory GHSA-x68m-c7jf-2572 lists affected ranges: Packagist getkirby/cms >=0 =5.0.0 <=5.3.3)

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