The PAN-OS response for GlobalProtect Gateway in Palo Alto Networks PAN-OS 6.1.21 and earlier, PAN-OS 7.1.18 and earlier, PAN-OS 8.0.11 and earlier may allow an unauthenticated attacker to inject arbitrary JavaScript or HTML. PAN-OS 8.1 is NOT affected.
https://security.paloaltonetworks.com/CVE-2018-10139