In Zammad before 6.3.1, a Ruby gem bundled by Zammad is installed with world-writable file permissions. This allowed a local attacker on the server to modify the gem's files, injecting arbitrary code into Zammad processes (which run with the environment and permissions of the Zammad user).

An issue was discovered in Zammad before 6.3.0. Users with customer access to a ticket could have accessed time accounting details of this ticket via the API. This data should be available only to agents.

An issue was discovered in Zammad before 6.3.0. An authenticated agent could perform a remote Denial of Service attack by calling an endpoint that accepts a generic method name, which was not properly sanitized against an allowlist.