Checkmk <2.5.0p10 Agent Receiver Auth Bypass via TLS Client Cert Verification
CVE-2026-15576 Published on August 21, 2026
Agent receiver accepts mTLS requests without a client certificate
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.
Weakness Type
Missing Authentication for Critical Function
The software does not perform any authentication for functionality that requires a provable user identity or consumes a significant amount of resources.
Products Associated with CVE-2026-15576
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Affected Versions
Checkmk GmbH Checkmk:- Version 2.5.0 and below 2.5.0p10 is affected.