Cyber Resilience

CVE-2021-40906

Medium

Published: 25 March 2022

Published
25 March 2022
Modified
21 November 2024
KEV Added
Patch
CVSS Score v3.1 6.1 CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N
EPSS Score 0.0062 70.6th percentile
Risk Priority 13 60% EPSS · 20% KEV · 20% CVSS

Summary

CVE-2021-40906 is a medium-severity Cross-site Scripting (CWE-79) vulnerability in Checkmk Checkmk. Its CVSS base score is 6.1 (Medium).

Operationally, ranked in the top 29.4% of CVEs by exploit likelihood; it is not currently listed in the CISA KEV catalog.

This vulnerability is AI-related — categorised as Machine Learning Libraries.

EU & UK References

Vulnerability details

CheckMK Raw Edition software (versions 1.5.0 to 1.6.0) does not sanitise the input of a web service parameter that is in an unauthenticated zone. This Reflected XSS allows an attacker to open a backdoor on the device with HTML content…

more

and interpreted by the browser (such as JavaScript or other client-side scripts) or to steal the session cookies of a user who has previously authenticated via a man in the middle. Successful exploitation requires access to the web service resource without authentication.

CWE(s)

AI Security AnalysisAI

AI Category
Machine Learning Libraries
Risk Domain
N/A
OWASP Top 10 for LLMs 2025
None mapped
Classification Reason
Matched keywords: backdoor

Related Threats

Affected Assets

checkmk
checkmk
1.6.0 · 1.5.0 — 1.6.0
tribe29
checkmk
1.6.0b10, 1.6.0b11, 1.6.0p10, 1.6.0p17, 1.6.0p18

Mitigating Controls

Likely Mitigating Controls AI

Per-CVE control mapping for this CVE has not run yet; the list below is derived from the weakness types (CWEs) cited in the NVD entry.

addresses: CWE-79

Penetration testing submits XSS payloads to web applications, detecting cross-site scripting flaws for subsequent remediation.

addresses: CWE-79

Validates web inputs to reject script-related content that could produce XSS.

addresses: CWE-79

Output validation against expected content can reject or sanitize script content in generated web pages, reducing XSS exploitability.

References