6.9

CVE-2026-15576: checkmk gmbh checkmk

CVSS: 6.9v4.0MediumDeferred
AliasesUBUNTU-CVE-2026-15576
Published 21-08-2026Last modified 21-08-2026
Open JSON

Vulnerability summary

CVE-2026-15576 is a medium (CVSS 6.9) vulnerability in checkmk gmbh checkmk. EPSS estimates a 0.45% chance of exploitation in the next 30 days, higher than 38.2% of scored vulnerabilities.

Overall risk
28/100
0100
Medium · default modelHow is this calculated?
CVSS score
6.9/10
010
Medium · v4.0 (CVE.org)
EPSS score
0.45%
0%100%
Low · +0.18 pp in 30 days
KEVNot listedIn no KEV catalog
RansomwareNone recordedNo known use recorded
Public exploits0No public exploits recorded

Timeline

  1. 21-08-2026
    PublishedVulnerability first disclosed.
  2. 21-08-2026
    Last modifiedVulnerability information updated.

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.

CVSS metrics

3 scores · 3 sources · 1 version

EPSS trend

Probability

0.45%

Chance of exploitation in the next 30 days

Percentile

38%

Versus all other CVEs

30-day change

+0.18 pp

From 0.27% on 21-09-2026

21-09-202621-10-2026
EPSS score
0.45%

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
Ubuntu1 product
  • check-mkAll versions (No fix recorded)

2 vendors · 2 products

References

3 links