Improper authentication in the agent receiver of Checkmk <2.5.0p10 allows an unauthenticated remote attacker to bypass mutual TLS client certificate… (CVE-2026-15576)
Checkmk versions prior to 2.5.0p10 contain an improper authentication vulnerability in the agent receiver component. This flaw allows an unauthenticated remote attacker to bypass mutual TLS client certificate verification for relay endpoints by using a fixed placeholder identity in the request URL. The vulnerability affects only the Cloud, Ultimate, and Ultimate MT editions, as other editions do not expose relay endpoints. The impact is limited to integrity and availability. No known exploits are reported in the wild, and no official patch information is provided.
AI Analysis
Technical Summary
CVE-2026-15576 describes an authentication bypass vulnerability in Checkmk agent receiver versions before 2.5.0p10. An unauthenticated remote attacker can circumvent mutual TLS client certificate verification of relay endpoints by supplying a fixed placeholder identity in the request URL. This improper authentication issue affects only specific editions (Cloud, Ultimate, Ultimate MT) that expose relay endpoints. The vulnerability results in limited impact on system integrity and availability.
Potential Impact
The vulnerability allows an unauthenticated attacker to bypass mutual TLS client certificate verification on relay endpoints, potentially compromising the integrity and availability of affected Checkmk installations. However, the impact is described as limited, and no active exploitation has been reported.
Mitigation Recommendations
Patch status is not yet confirmed — check the vendor advisory for current remediation guidance. Until an official fix is available, restrict access to relay endpoints and monitor for suspicious activity related to authentication bypass attempts. Only the Cloud, Ultimate, and Ultimate MT editions are affected; other editions are not vulnerable due to lack of exposed relay endpoints.
Improper authentication in the agent receiver of Checkmk <2.5.0p10 allows an unauthenticated remote attacker to bypass mutual TLS client certificate… (CVE-2026-15576)
Description
Checkmk versions prior to 2.5.0p10 contain an improper authentication vulnerability in the agent receiver component. This flaw allows an unauthenticated remote attacker to bypass mutual TLS client certificate verification for relay endpoints by using a fixed placeholder identity in the request URL. The vulnerability affects only the Cloud, Ultimate, and Ultimate MT editions, as other editions do not expose relay endpoints. The impact is limited to integrity and availability. No known exploits are reported in the wild, and no official patch information is provided.
CVSS v4.0
Affected software
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Weaknesses
AI-Powered Analysis
Machine-generated threat intelligence
Technical Analysis
CVE-2026-15576 describes an authentication bypass vulnerability in Checkmk agent receiver versions before 2.5.0p10. An unauthenticated remote attacker can circumvent mutual TLS client certificate verification of relay endpoints by supplying a fixed placeholder identity in the request URL. This improper authentication issue affects only specific editions (Cloud, Ultimate, Ultimate MT) that expose relay endpoints. The vulnerability results in limited impact on system integrity and availability.
Potential Impact
The vulnerability allows an unauthenticated attacker to bypass mutual TLS client certificate verification on relay endpoints, potentially compromising the integrity and availability of affected Checkmk installations. However, the impact is described as limited, and no active exploitation has been reported.
Mitigation Recommendations
Patch status is not yet confirmed — check the vendor advisory for current remediation guidance. Until an official fix is available, restrict access to relay endpoints and monitor for suspicious activity related to authentication bypass attempts. Only the Cloud, Ultimate, and Ultimate MT editions are affected; other editions are not vulnerable due to lack of exposed relay endpoints.
Technical Details
- Gcve Source
- db.gcve.eu
- Osv Id
- GHSA-8fww-64wc-46pf
- Osv Schema Version
- 1.4.0
- Aliases
- ["CVE-2026-15576"]
- Ecosystems
- []
- Database Specific Severity
- MODERATE
- Cvss Version
- 4.0
Threat ID: 6a885f17acd9273b493f7881
Added to database: 08/21/2026, 14:22:15 UTC
Last enriched: 08/21/2026, 14:26:18 UTC
Last updated: 08/22/2026, 03:51:58 UTC
Views: 3
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