# CVE-2023-23586: Use after free in io_uring in the Linux Kernel

> A use-after-free in the Linux kernel io_uring subsystem allows local attackers to leak kernel memory contents to user space.

- **Severity:** Medium 5.5 (`CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N`)
- **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:** 17 Feb 2023
- **Updated:** 12 Mar 2025
- **Also known as:** DEBIAN-CVE-2023-23586, GHSA-h86q-32m7-8f9v, UBUNTU-CVE-2023-23586

## What is CVE-2023-23586?

CVE-2023-23586 is a medium-severity use after free vulnerability in Linux kernel, published on 17 Feb 2023. It can only be exploited from the same machine or local network, with no action from the victim.

### Official description

Due to a vulnerability in the io_uring subsystem, it is possible to leak kernel memory information to the user process. timens_install calls current_is_single_threaded to determine if the current process is single-threaded, but this call does not consider io_uring's io_worker threads, thus it is possible to insert a time namespace's vvar page to process's memory space via a page fault. When this time namespace is destroyed, the vvar page is also freed, but not removed from the process' memory, and a next page allocated by the kernel will be still available from the user-space process and can leak memory contents via this (read-only) use-after-free vulnerability. We recommend upgrading past version 5.10.161 or commit  788d0824269bef539fe31a785b1517882eafed93 https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/io_uring

Weakness: CWE-416 (Use After Free)

## Which versions are affected by CVE-2023-23586?

It affects 1 product.


Products: Linux kernel.

## How do I fix CVE-2023-23586?

Upgrade to a fixed version.

## Is CVE-2023-23586 being exploited?

There is no known exploitation of CVE-2023-23586 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-2023-23586 and fix it if it is affected.

What it is: CVE-2023-23586 is a medium-severity use after free vulnerability in Linux kernel, published on 17 Feb 2023. 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-2023-23586 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-2023-23586/ (Markdown: https://insights.sbomify.com/CVE-2023-23586/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2023-23586
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2023-23586
- OSV: https://osv.dev/vulnerability/CVE-2023-23586

---
From sbomify Insights: https://insights.sbomify.com/CVE-2023-23586/
Summaries are generated and may contain mistakes; the official description above is the record.