Netgate pfSense FRR package (pfSense-pkg-frr) 2.0.21 and source revision 2.1.21 contain an OS command injection vulnerability in the FRR status filter. An authenticated WebGUI user with only the page-status-frr privilege can supply a filter value that breaks out of a single-quoted sed expression into which escapeshellarg() output is concatenated. Shell command substitution is then evaluated by a popen() pipeline, allowing attacker-selected commands to execute as root. There are updated FRR packages for pfSense Plus 26.07/26.03.1 and CE 2.9.0/2.8.1.