Inappropriate error handling in Tribe29 Checkmk <= 2.1.0p25, <= 2.0.0p34, <= 2.2.0b3 (beta), and all versions of Checkmk 1.6.0 causes the symmetric encryption of agent data to fail silently and transmit the data in plaintext in certain configurations.

A permission issue affects users that deployed the shipped version of the Checkmk Debian package. Packages created by the agent bakery (enterprise editions only) were not affected. Using the shipped version of the agents, the maintainer scripts located at /var/lib/dpkg/info/ will be owned by the user and the group with ID 1001. If such a user exists on the system, they can change the content of these files (which are then executed by root). This leads to a local privilege escalation on the monitored host. Version 1.6 through 1.6.9p29, version 2.0 through 2.0.0p26, version 2.1 through 2.1.0p3, and version 2.2.0i1 are affected.

In Checkmk before 1.6.0p29, 2.x before 2.0.0p25, and 2.1.x before 2.1.0b10, a site user can escalate to root by editing an OMD hook symlink.

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.