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

> A race condition in the Linux kernel io_uring subsystem allows attackers to potentially execute arbitrary code or escalate privileges via improper buffer list recycling checks.

- **Severity:** High 7.8 (`CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Any signed-in user
- **Attackable:** Local or same network only
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 8 May 2026
- **Updated:** 19 Oct 2026
- **Also known as:** BELL-CVE-2026-43366, DEBIAN-CVE-2026-43366, GHSA-g6hq-4292-hhwx, ROOT-OS-UBUNTU-2404-CVE-2026-43366, UBUNTU-CVE-2026-43366

## What is CVE-2026-43366?

CVE-2026-43366 is a high-severity vulnerability in Linux kernel, published on 8 May 2026. It can only be exploited from the same machine or local network, with no action from the victim.

### Official 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.

Weakness: CWE-362 (Concurrent Execution using Shared Resource with Improper Synchronization)

## Which versions are affected by CVE-2026-43366?

It affects 1 product.


Products: Linux kernel.

## How do I fix CVE-2026-43366?

Apply the vendor's patch.

## Is CVE-2026-43366 being exploited?

There is no known exploitation of CVE-2026-43366 in the wild and no public exploit code.

## Other vulnerabilities in Linux kernel

- [CVE-2026-53266](https://insights.sbomify.com/CVE-2026-53266/): Linux Kernel Out-of-Bounds Write (high 8.8, exploited in the wild)
- [CVE-2013-6282](https://insights.sbomify.com/CVE-2013-6282/): Linux Kernel Improper Input Validation (high 8.8, exploited in the wild)
- [CVE-2022-0185](https://insights.sbomify.com/CVE-2022-0185/): Linux Kernel Heap-Based Buffer Overflow (high 8.4, exploited in the wild)
- [CVE-2013-2094](https://insights.sbomify.com/CVE-2013-2094/): Linux Kernel Privilege Escalation (high 8.4, exploited in the wild)
- [CVE-2026-53362](https://insights.sbomify.com/CVE-2026-53362/): Linux Kernel Unspecified (high 7.8, exploited in the wild)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-43366 and fix it if it is affected.

What it is: CVE-2026-43366 is a high-severity vulnerability in Linux kernel, published on 8 May 2026. It can only be exploited from the same machine or local network, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2026-43366 in the wild and no public exploit code.

Affected product: Linux kernel. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-43366/ (Markdown: https://insights.sbomify.com/CVE-2026-43366/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-43366
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-43366
- OSV: https://osv.dev/vulnerability/CVE-2026-43366

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-43366/
Summaries are generated and may contain mistakes; the official description above is the record.