# CVE-2023-2236: Use-after-free in Linux kernel's Performance Events subsystem

> A use-after-free in the Linux kernel io_uring subsystem allows local attackers to escalate privileges.

- **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:** 1 May 2023
- **Updated:** 5 Mar 2025
- **Also known as:** DEBIAN-CVE-2023-2236, GHSA-j4r5-9qqm-p694, UBUNTU-CVE-2023-2236

## What is CVE-2023-2236?

CVE-2023-2236 is a high-severity use after free vulnerability in Linux kernel, published on 1 May 2023. It can only be exploited from the same machine or local network, with no action from the victim.

### Official description

A use-after-free vulnerability in the Linux Kernel io_uring subsystem can be exploited to achieve local privilege escalation.

Both io_install_fixed_file and its callers call fput in a file in case of an error, causing a reference underflow which leads to a use-after-free vulnerability.

We recommend upgrading past commit 9d94c04c0db024922e886c9fd429659f22f48ea4.

Weakness: CWE-416 (Use After Free)

## Which versions are affected by CVE-2023-2236?

It affects 2 products.


Products: Linux kernel, Netapp Hci Baseboard Management Controller.

## How do I fix CVE-2023-2236?

Apply the vendor's patch.

## Is CVE-2023-2236 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2023-2236 exists.

## 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-2023-2236 and fix it if it is affected.

What it is: CVE-2023-2236 is a high-severity use after free vulnerability in Linux kernel, published on 1 May 2023. It can only be exploited from the same machine or local network, with no action from the victim.
Exploitation: It is not confirmed as exploited in the wild, but public exploit code for CVE-2023-2236 exists.

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-2023-2236/ (Markdown: https://insights.sbomify.com/CVE-2023-2236/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2023-2236
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2023-2236
- OSV: https://osv.dev/vulnerability/CVE-2023-2236

---
From sbomify Insights: https://insights.sbomify.com/CVE-2023-2236/
Summaries are generated and may contain mistakes; the official description above is the record.