CVE-2026-15576
Agent receiver accepts mTLS requests without a client certificate
- State
- Published
- Severity
- 6.9 Medium
- Published
- Aug 21, 2026
- Updated
- Aug 21, 2026
- Reserved
- Jul 13, 2026
Description
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.
Scores
| CVSS | Score | Vector | Source |
|---|---|---|---|
| 4.0 | 6.9 Medium | 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 | Checkmk |
Weaknesses
- CWE-306 Missing Authentication for Critical Function
Affected Products
| Product | Versions |
|---|---|
CheckmkCheckmk GmbH |
|
References
- https://checkmk.com/werk/20174vendor-advisory
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