Semaphore UI through 2.19.16 RCE via Task Environment Ansible Variable Override

Semaphore UI through 2.19.16 contains a remote code execution vulnerability that allows users with the task_runner role to override protected Ansible variables by supplying arbitrary keys in the task environment JSON. Attackers can POST tasks setting ansible_ssh_common_args with a ProxyCommand or ansible_connection=local to execute commands as the Semaphore server user, exposing encryption keys, SSH keys and stored secrets.