What is CVE-2026-3103?

CVE-2026-3103 is a medium-severity vulnerability in Checkmk, classified under Incorrect Authorization. CVSS score: 5.4/10. Published 2026-03-04.

How severe is CVE-2026-3103?

Medium severity. CVSS v3 base score is 5.4 out of 10.

Auth bypass in Checkmk

CVE-2026-3103

A logic error in the remove_password() function in Checkmk GmbH's Checkmk versions <2.4.0p23, <2.3.0p43, and 2.2.0 (EOL) allows a low-privileged user to cause data loss.

Vulnerability class: Broken Access Control

Published 2026-03-04 · last modified 2026-06-17.

CVSS v3 metric

CVSS v3 base score 5.4 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:L.

EPSS exploit prediction

EPSS: 0.003 (19.1th percentile), scored 2026-09-30.

Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 19th percentile — 19.1% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS over last 30 days · oldest: 0.002 · newest: 0.003 · change: +0.001

Affected products

Checkmk — versions 2.2.0, 2.3.0, 2.4.0
Checkmk Gmbh — versions 2.4.0, 2.3.0, 2.2.0

Weakness classification (CWE)

CWE-863 — Incorrect Authorization

References

checkmk.com/werk/19041 (Mitigation, Vendor Advisory)

Frequently asked questions

What is CVE-2026-3103?: CVE-2026-3103 is a medium-severity vulnerability in Checkmk, classified under Incorrect Authorization. CVSS score: 5.4/10. Published 2026-03-04.
How severe is CVE-2026-3103?: Medium severity. CVSS v3 base score is 5.4 out of 10.