Medium 6.9Published Aug 21, 2026

CVE-2026-15576Agent receiver accepts mTLS requests without a client certificate

Updated under an hour ago (2026-10-19 08:23 UTC)

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It affects Checkmk GmbH Checkmk. Add what you run to find out whether that includes you.

No exploitation reported and no EPSS estimate yet.

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Every CVE for Checkmk GmbH Checkmk

Exploited in the last 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.

CVSS: 6.9 MEDIUM (v4.0, CNA)CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:L/VA:L/SC:N/SI:N/SA:N
Weakness (CWE): CWE-306
Known exploited: Not in CISA's KEV catalog
EPSS (exploitation in the next 30 days): Not loaded for this CVE
Assigned by: Checkmk
NVD analysis: Deferred
Record last updated: Aug 21, 2026
First seen by InfoSec Signals: Oct 9, 2026

Affected products

Affected products

Checkmk GmbH Checkmk checkmk:checkmk (from the name)	from 2.5.0 before 2.5.0p10	CNA record

References

https://checkmk.com/werk/20174vendor-advisory

The CVE record on cve.org NVD's entry

The CVE record is authoritative. Products marked “from the name” were identified from the CNA's free-text names, not a CPE, and are matched less certainly. This product uses the NVD API but is not endorsed or certified by the NVD.