An issue was discovered in Pulse Secure Pulse Connect Secure (PCS) through 2020-04-06. The applet in tncc.jar, executed on macOS, Linux, and Solaris clients when a Host Checker policy is enforced, allows a man-in-the-middle attacker to perform OS command injection attacks (against a client) via shell metacharacters to the doCustomRemediateInstructions method, because Runtime.getRuntime().exec() is used.