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.