Agent receiver certificate confusion allows authentication with a certificate issued for another endpoint (CVE-2026-15937) | HOL Guard CVE

Unknown severity · Source severity not reportedCVE-2026-15937

Agent receiver certificate confusion allows authentication with a certificate issued for another endpoint

Answer in brief

CVE-2026-15937 records a Unknown severity vulnerability in Agent receiver certificate confusion allows authentication with a certificate issued for another endpoint. The current sources do not mark it as known exploited. The current feed maps Checkmk GmbH/Checkmk (generic). Check affected ranges and fixed versions before updating.

Analysis pending evidence review

HOL Guard separates source facts from reviewed analysis. See the methodology.

Published Sep 4, 2026Updated Sep 4, 2026Source checked Sep 4, 2026First seen by HOL Sep 4, 2026Material review Sep 4, 2026

Upstream Advisory

Key facts

Risk: Unknown severitySource severity not reported
Exploitation: Not marked as known exploited
Affected software: 1 mapped package or product
Fix availability: Available

Why this deserves its current priority

A CVSS score is not reported in the current record. The current sources do not mark it as known exploited. Treat this as a source-backed prioritization signal, not a statement about your environment.

Analysis status

Analysis pending evidence review

Factual feed record only; HOL analysis is not approved for indexing. Read the methodology.

Affected scope and exposure questions

The current feed maps Checkmk GmbH/Checkmk (generic). Check affected ranges and fixed versions before updating.

Mapped affected packages and fixed versions
Package	Affected range	Fixed version
Checkmk GmbH/Checkmkgeneric	>=2.5.0 <2.5.0p10	2.5.0p10

Recommended response

Check inventory. Check lockfiles and deployed manifests for Checkmk GmbH/Checkmk.
Review the reported fix. Update Checkmk GmbH/Checkmk to 2.5.0p10 if you use the affected versions. Test the change in a non-production environment first.

Evidence timeline and material changes

Published upstream
Sep 4, 2026
Evidence: source:cvelist:source_dates:source-dates:record
Source modified
Sep 4, 2026
Evidence: source:cvelist:source_dates:source-dates:record
First seen by HOL
Sep 4, 2026

Sources and claim methodology

Source referencecheckmk.com

Upstream source 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.

Quoted source text, attributed separately from HOL analysis.