NP7 ASIC Offload Engine Silently Drops Packets with IP Options Headers
Hardware fastpath processors on NP7-equipped FortiGates fail to punt transit packets with IPv4 options headers to the host CPU, silently discarding packets and breaking specialized industrial control, video multicast, and routing protocols.
Technical Root Cause Analysis
The NP7 (Network Processor 7) ASIC offload engine processes IPv4 sessions at wire-speed by parsing standard 20-byte packet headers directly in hardware silicon. When specialized enterprise or industrial applications inject IPv4 Options fields (such as Router Alert Option Type 148 used in IGMP/RSVP or custom CIP headers), the header length exceeds 20 bytes.
In affected FortiOS builds, the NP7 microcode parser marks the packet as an invalid header structure instead of initiating an exception redirect (slow-path punt) to the Linux host CPU. The packet is silently discarded inside the ASIC pipeline and the hardware counter ip_opt_drop increments without generating any firewall event log.
Affected Firmware & Blast Radius Matrix
| FortiOS Branch | Vulnerable Builds | Confirmed Clean Build | Status & Workaround |
|---|---|---|---|
| FortiOS 7.2 | 7.2.0 – 7.2.5 | 7.2.6+ | Disable auto-asic-offload on policy |
| FortiOS 7.4 | 7.4.0 – 7.4.2 | 7.4.3+ | NP7 microcode slow-path patch included |
| FortiOS 7.0 | Limited Impact | 7.0.12+ | Applies to NP7 hardware models only |
Platform Impact: All FortiGate appliances powered by NP7 processors (FG-1800F, FG-2600F, FG-3000F, FG-3200F, FG-4200F, FG-4400F).
Step 01: Free Verification CLI (Safe Read-Only)
Execute these commands to dump NP7 hardware drop registers and confirm if IP options packets are being discarded:
Diagnostic Commands
# 1. Dump NP7 ASIC hardware drop registers
diagnose npu np7 drop 0
# 2. Check general NP7 hardware processor statistics
diagnose npu np7 stat 0
# 3. Check active hardware-offloaded session count
diagnose npu np7 session-stats
# 4. Search active sessions for NPU offload flags
diagnose sys session list | grep -i npuRemediation & Workaround Steps (Teaser Preview)
Follow the complete ASIC bypass and hardware tuning guide on the Ferrite interactive platform:
Frequently Asked Questions
The NP7 hardware parser drops IPv4 packets containing header options instead of punting them to the Linux host CPU for software evaluation.
Disabling auto-asic-offload only affects the specific firewall policy where it is configured; all other traffic continues passing through NP7 hardware at multi-gigabit speeds.
FortiOS 7.2.6 and 7.4.3 include updated NP7 driver microcode that properly diverts IP options packets to CPU slowpath.