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Unscored Public exploit CVE-2021-40906 EUVD-2021-28061GHSA-jv73-q4rg-p7qh

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…

Published Mar 25, 2022 · Updated Jul 9, 2026 · Assigned by mitre

Package: check-mk Ecosystem: Ubuntu

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.

Fixed in Linux distributions

Distributions backport fixes, so the version that fixes this vulnerability differs per release — upgrade to at least the version shown. From the distributions' security trackers and advisories.

Ubuntu

Security tracker ↗
ReleasePackageFixed inAdvisory
Ubuntu 18.04 LTS check-mk 1.2.8p16-1ubuntu0.2 USN-5527-1

Public exploits

Exploit or proof-of-concept code for this vulnerability is publicly available, which lowers the bar for attackers. Treat it as a reason to patch sooner.

Third-party code, not reviewed by us. Public PoCs are sometimes fake or contain malware. Read the code first and run it only in an isolated lab, against systems you are authorised to test.

GitHub 1 repository

Sources: PoC-in-GitHub, Metasploit Framework, Exploit-DB — updated daily. Only links are listed; no exploit code is hosted here.

Advisories 1

References