CVE-2026-8833: Checkmk

Medium severity, CVSS 5.4. EPSS: 0.2% chance of exploitation in the next 30 days.

Improper neutralization of HTML-encoded characters in the URL validation function in Checkmk <2.5.0p5, <2.4.0p31, <2.3.0p48, and all 2.2.0 versions allows an authenticated user to bypass URL validation and inject malicious URLs such as javascript: URIs, resulting in cross-site scripting when another user interacts with the crafted link.

Affected products

• Checkmk Checkmk: version 2.2.0 only; version 2.3.0 only; version 2.4.0 only; version 2.5.0 only

Published 2026-06-08. Last modified 2026-10-06.