Pulse Secure · Pulse Connect Secure · CVE-2020-11581
**Name of the Vulnerable Software and Affected Versions**
Pulse Secure Pulse Connect Secure (PCS) versions prior to 2020-04-06
**Description**
The issue allows a man-in-the-middle attacker to perform OS command injection attacks against a client via shell metacharacters to the `doCustomRemediateInstructions` method. This is because `Runtime.getRuntime().exec()` is used. The applet in tncc.jar, executed on macOS, Linux, and Solaris clients when a Host Checker policy is enforced, is vulnerable to this attack.
**Recommendations**
For Pulse Secure Pulse Connect Secure (PCS) versions prior to 2020-04-06, as a temporary workaround, consider disabling the `doCustomRemediateInstructions` method until a patch is available. Restrict access to the tncc.jar applet to minimize the risk of exploitation. Avoid using shell metacharacters in the affected method to prevent OS command injection attacks.