The GlobalProtect external interface in Palo Alto Networks PAN-OS before 6.1.17, 7.x before 7.0.15, 7.1.x before 7.1.9, and 8.x before 8.0.2 provides different error messages for failed login attempts depending on whether the username exists, which allows remote attackers to enumerate account names and conduct brute-force attacks via a series of requests, aka PAN-SA-2017-0014 and PAN-72769.