5.3

CVE-2026-15937: checkmk gmbh checkmk Improper Certificate Validation

CVSS: 5.3v4.0MediumDeferred
Published 04-09-2026Last modified 04-09-2026
Open JSON

Vulnerability summary

CVE-2026-15937 is a medium (CVSS 5.3) Improper Certificate Validation vulnerability in checkmk gmbh checkmk. EPSS estimates a 0.14% chance of exploitation in the next 30 days, higher than 3% of scored vulnerabilities.

Overall risk
21/100
0100
Low · default modelHow is this calculated?
CVSS score
5.3/10
010
Medium · v4.0 (CVE.org)
EPSS score
0.14%
0%100%
Low · 0.00 pp in 30 days
KEVNot listedIn no KEV catalog
RansomwareNone recordedNo known use recorded
Public exploits0No public exploits recorded

Timeline

  1. 04-09-2026
    PublishedVulnerability first disclosed.
  2. 04-09-2026
    Last modifiedVulnerability information updated.

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 metrics

2 scores · 2 sources · 1 version

EPSS trend

Probability

0.14%

Chance of exploitation in the next 30 days

Percentile

3%

Versus all other CVEs

30-day change

0.00 pp

From 0.14% on 21-09-2026

21-09-202621-10-2026
EPSS score
0.14%

Known exploited

Compare KEV catalogs

Not in any of the 3 tracked catalogs.

Public exploits

0 found

No public exploits indexed.

Weaknesses

CWE · root cause

Affected systems

Checkmk gmbh1 product

1 vendor · 1 product

References

1 links