The earliest recollection of this bug is traced back to PAN-OS 8.1.15 - January 09, 2024.
This bug is fixed in PAN-OS versions 9.1.3, 8.1.15.
A fix was made to address a buffer overflow vulnerability in PAN-OS that allowed an unauthenticated attacker to disrupt system processes and potentially execute arbitrary code with root privileges by sending a malicious request to the Captive Portal or Multi-Factor Authentication interface ( CVE-2020-2040 ).
For more information:
https://docs.paloaltonetworks.com/pan-os/8-1/pan-os-release-notes/pan-os-8-1-addressed-issues/pan-os-8-1-15-addressed-issues
https://docs.paloaltonetworks.com/pan-os/9-1/pan-os-release-notes/pan-os-9-1-addressed-issues/pan-os-9-1-3-addressed-issues