What is CVE-2021-40904?

CVE-2021-40904 is a high-severity vulnerability in Checkmk, classified under Incorrect Default Permissions. CVSS score: 8.8/10. Published 2022-03-25.

How severe is CVE-2021-40904?

High severity. CVSS v3 base score is 8.8 out of 10.

Is CVE-2021-40904 known to be exploited?

9 public proof-of-concept repositories are indexed. Not currently listed in the CISA KEV catalog.

Vulnerability in Checkmk

CVE-2021-40904

The web management console of CheckMK Raw Edition (versions 1.5.0 to 1.6.0) allows a misconfiguration of the web-app Dokuwiki (installed by default), which allows embedded php code. As a result, remote code execution is achieved. Successful exploitation requires access to the web management interface, either with valid credentials or with a hijacked session by a user with the role of administrator.

Published 2022-03-25 · last modified 2026-07-09.

CVSS v3 metric

CVSS v3 base score 8.8 (High). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H.

EPSS exploit prediction

EPSS: 0.037 (89.3th percentile), scored 2026-10-01.

Low probability of exploitation in the next 30 days, but still tracked. 89th percentile — 89.3% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS over last 30 days · oldest: 0.037 · newest: 0.037 · change: 0.000

Affected products

Checkmk

Weakness classification (CWE)

CWE-276 — Incorrect Default Permissions

Public proof-of-concept exploits

References

af854a3a-2127-422b-91ae-364da2661108 (Product)
github.com/Edgarloyola/CVE-2021-40904 (Exploit, Patch, Third Party Advisory)

Frequently asked questions

What is CVE-2021-40904?: CVE-2021-40904 is a high-severity vulnerability in Checkmk, classified under Incorrect Default Permissions. CVSS score: 8.8/10. Published 2022-03-25.
How severe is CVE-2021-40904?: High severity. CVSS v3 base score is 8.8 out of 10.
Is CVE-2021-40904 known to be exploited?: 9 public proof-of-concept repositories are indexed. Not currently listed in the CISA KEV catalog.