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.
Published: 2026-08-21
Score: 6.9 Medium
EPSS: n/a
KEV: No
Impact: n/a
Action: n/a
AI Analysis

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Remediation

No vendor fix or workaround currently provided.

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Tracking

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Advisories

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References
History

Fri, 21 Aug 2026 12:30:00 +0000

Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'yes', 'Exploitation': 'none', 'Technical Impact': 'partial'}, 'version': '2.0.3'}


Fri, 21 Aug 2026 11:15:00 +0000

Type Values Removed Values Added
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.
Title Agent receiver accepts mTLS requests without a client certificate
First Time appeared Checkmk
Checkmk checkmk
Weaknesses CWE-306
CPEs cpe:2.3:a:checkmk:checkmk:*:*:*:*:*:*:*:*
Vendors & Products Checkmk
Checkmk checkmk
References
Metrics cvssV4_0

{'score': 6.9, 'vector': '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'}


cve-icon MITRE

Status: PUBLISHED

Assigner: Checkmk

Published:

Updated: 2026-08-21T11:53:45.355Z

Reserved: 2026-07-13T08:39:03.953Z

Link: CVE-2026-15576

cve-icon Vulnrichment

Updated: 2026-08-21T11:53:41.230Z

cve-icon NVD

Status : Received

Published: 2026-08-21T11:17:04.463

Modified: 2026-08-21T12:16:23.090

Link: CVE-2026-15576

cve-icon Redhat

No data.

cve-icon OpenCVE Enrichment

Updated: 2026-08-21T12:30:14Z

Weaknesses
  • CWE-306

    Missing Authentication for Critical Function