What’s Vulnerable › Vulnerabilities
CVE-2026-15576: Agent receiver accepts mTLS requests without a client certificate
- Severity: medium (CVSS 6.9 v4.0)
- Exploited in the wild: not listed in CISA KEV
- EPSS: 0.5% probability of exploitation in the next 30 days
- Public exploit or detection template: none known
- Published: 2026-08-21 · updated 2026-10-16
- Weakness: CWE-306
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.
Affected products
- Checkmk GmbH Checkmk: from 2.5.0 before 2.5.0p10 — fixed in 2.5.0p10
How to fix
Upgrade to a fixed version: Checkmk GmbH Checkmk 2.5.0p10. Check the vendor advisory for mitigations.
References
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