CVE-2026-15576 — 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 endpoi…
Published: 2026-08-21 · CVSS: 6.9 · CVSS 4.0
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.
Source: CVE Program · Revision 8b16575c39f1e1810c5e863010da073d2d3285e7