A code injection vulnerability has been discovered in the Robot Operating System 2 (ROS 2) 'ros2topic' command-line tool, affecting all ROS 2 distributions from Crystal Clemmys up to and including Lyrical Luth and Rolling Ridley. The vulnerability lies in the 'hz' verb, which reports the publishing rate of a topic and accepts a user-provided Python expression via the --filter option. This input is passed directly to the eval() function without sanitization, allowing a local user to craft and execute arbitrary code.