CVE-2021-40906

MEDIUM

CheckMK Raw Edition 1.5.0-1.6.0 - Unauthenticated Reflected Cross-Site Scripting via Web Service Parameter

Title source: llm
STIX 2.1

Exploitation Summary

EIP tracks 1 public exploit for CVE-2021-40906. PoCs published by Edgarloyola.

AI-analyzed exploit summary This repository provides a detailed writeup and proof-of-concept for CVE-2021-40906, a reflected XSS vulnerability in CheckMK Management Web Console versions 1.5.0 to 1.5.0p25. The vulnerability allows unauthenticated attackers to execute arbitrary JavaScript in the context of a user's browser session.

Description

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 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.

Exploits (1)

nomisec WRITEUP 1 stars
by Edgarloyola · poc
https://github.com/Edgarloyola/CVE-2021-40906

This repository provides a detailed writeup and proof-of-concept for CVE-2021-40906, a reflected XSS vulnerability in CheckMK Management Web Console versions 1.5.0 to 1.5.0p25. The vulnerability allows unauthenticated attackers to execute arbitrary JavaScript in the context of a user's browser session.

Classification
Writeup 90%
Attack Type
Xss
Complexity
Trivial
Reliability
Reliable
Target: CheckMK Management Web Console 1.5.0 to 1.5.0p25
No auth needed
Prerequisites: Access to the unauthenticated web service resource
MITRE ATT&CK
devstral-2 · analyzed Feb 16, 2026 Full analysis →

References (2)

Core 2
Core References
Product x_refsource_misc
http://checkmk.com
Third Party Advisory x_refsource_misc
https://github.com/Edgarloyola/CVE-2021-40906

Scores

CVSS v3 6.1
EPSS 0.0099
EPSS Percentile 58.1%
Attack Vector NETWORK
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N

Details

CWE
CWE-79
Status published
Products (7)
checkmk/checkmk 1.6.0 (31 CPE variants)
checkmk/checkmk 1.5.0 - 1.6.0
tribe29/checkmk 1.6.0b10
tribe29/checkmk 1.6.0b11
tribe29/checkmk 1.6.0p10
tribe29/checkmk 1.6.0p17
tribe29/checkmk 1.6.0p18
Published Mar 25, 2022
Tracked Since Feb 18, 2026