CVE-2021-40906
MediumCVSS 6.1Exploitation Probability (EPSS)
Elevated risk58th percentile - higher than 58% of all known CVEs
Summary
CheckMK Raw Edition versions 1.5.0 to 1.6.0 do not sanitize input of a web service parameter in an unauthenticated zone. This Reflected XSS allows an attacker to open a backdoor with HTML content interpreted by the browser (e.g., JavaScript) or steal session cookies of an authenticated user via man-in-the-middle.
Risk Assessment
The risk for the organization includes session hijacking of administrators, theft of sensitive data, or execution of malicious scripts in the victim's browser context, potentially leading to privilege escalation and compromise of the monitoring system.
Recommendation
Immediately upgrade CheckMK Raw Edition to version 1.6.0p1 or later, which includes a fix for this vulnerability. Additionally, implement network traffic filtering and Content-Security-Policy headers.
Original NVD description (English source)
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.