CVE-2026-42051: Kirby: System API endpoint leaks license data and installed version to authenticated users

Severity: medium (CVSS 4.3 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.2% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2026-05-09 · updated 2026-07-24
Weakness: CWE-862

Description

Kirby is an open-source content management system. Prior to versions 4.9.0 and 5.4.0, the system API endpoint leaks license data and installed version to authenticated users. This issue has been patched in versions 4.9.0 and 5.4.0.

Affected products

getkirby kirby: before 4.9.0; from 5.0.0 before 5.4.0 — fixed in 4.9.0, 5.4.0

How to fix

Upgrade to a fixed version: getkirby kirby 4.9.0, 5.4.0. Check the vendor advisory for mitigations.

References

https://github.com/getkirby/kirby/releases/tag/4.9.0
https://github.com/getkirby/kirby/releases/tag/5.4.0
https://github.com/getkirby/kirby/security/advisories/GHSA-x68m-c7jf-2572

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