CVE-2026-15576: Checkmk GmbH Checkmk

Medium severity, CVSS 6.9. EPSS: 0.5% chance of exploitation in the next 30 days.

Improper authentication in the agent receiver of Checkmk <2.5.0p10 allows an unauthenticated remote attacker to bypass mutual TLS client certificate verification of relay endpoints by supplying a fixed placeholder identity in the request URL, resulting in limited impact on integrity and availability. Only the Cloud, Ultimate and Ultimate MT editions are affected, as other editions do not expose relay endpoints.

Affected products

• Checkmk GmbH Checkmk: from 2.5.0, before 2.5.0p10 (fixed in 2.5.0p10)

Published 2026-08-21. Last modified 2026-08-26.