Disclaimer

Known affected versions were inferred from fixed-version data and were not explicitly confirmed by the vendor: 8.1.15-h3, 9.1.4

The earliest recollection of this bug is traced back to PAN-OS 8.1.16 - July 22, 2025. This bug is fixed in PAN-OS versions 9.1.5, 8.1.16. Fixed an issue where TCP traffic dropped due to TCP sequence checking in an HA active/active configuration where traffic was asymmetric. Fixed an issue where TCP traffic dropped due to TCP sequence checking in a high availability (HA) active/active configuration where traffic was asymmetric. For more information: https://docs.paloaltonetworks.com/pan-os/8-1/pan-os-release-notes/pan-os-8-1-addressed-issues/pan-os-8-1-16-addressed-issues https://docs.paloaltonetworks.com/pan-os/9-1/pan-os-release-notes/pan-os-9-1-addressed-issues/pan-os-9-1-5-addressed-issues