In the MMM::Agent::Helpers::Network::add_ip function in MySQL Multi-Master Replication Manager (MMM) mmm_agentd 2.2.1 (for Linux), a specially crafted MMM protocol message can cause a shell command injection resulting in arbitrary command execution with the privileges of the mmm\_agentd process. An attacker that can initiate a TCP session with mmm\_agentd can trigger this vulnerability.