CVE-2026-15937: CWE-295: Improper Certificate Validation in Checkmk GmbH Checkmk
Description
Improper certificate validation in Checkmk <2.5.0p10 allows a relay and a push agent that share the same UUID to reuse each other's mTLS certificate to authenticate against agent receiver endpoints in either direction, because the endpoints do not verify that the certificate was issued by their own root certificate.
CVSS v4.0
Score 5.3medium
Affected software
Checkmk GmbH
Checkmk
Weaknesses
AI-Powered Analysis
Machine-generated threat intelligence
Technical Analysis
CVE-2026-15937 describes an improper certificate validation vulnerability (CWE-295) in Checkmk versions 2.5.0 and 2.5.0p10. The issue arises because agent receiver endpoints do not verify that the presented mTLS certificate was issued by their own root certificate. Consequently, a relay and a push agent that share the same UUID can reuse each other's mTLS certificates to authenticate in either direction, potentially bypassing intended authentication boundaries.
Potential Impact
The vulnerability allows unauthorized authentication between relay and push agents sharing the same UUID by reusing mTLS certificates. This could lead to unauthorized access to agent receiver endpoints within the affected Checkmk environment. The CVSS 4.0 base score is 5.3 (medium severity), indicating a moderate impact without requiring user interaction or high privileges.
Mitigation Recommendations
Patch status is not yet confirmed — check the vendor advisory for current remediation guidance. No official fix or temporary mitigation is currently documented. Users should monitor Checkmk vendor advisories for updates addressing this certificate validation issue.
Technical Details
- Data Version
- 5.2
- Assigner Short Name
- Checkmk
- Date Reserved
- 2026-07-16T08:40:57.255Z
- Cvss Version
- 4.0
- State
- PUBLISHED
Threat ID: 6a9a8354acd9273b494e27ec
Added to database: 09/04/2026, 08:37:40 UTC
Last enriched: 09/07/2026, 11:54:06 UTC
Last updated: 10/17/2026, 18:48:17 UTC
Views: 84
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