# CVE-2023-0240: Use after free in io_uring in the Linux Kernel

> A logic error in the Linux Kernel's io_uring implementation allows attackers to trigger a use-after-free, leading to privilege escalation.

- **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:** 30 Jan 2023
- **Updated:** 2 Aug 2024
- **Also known as:** DEBIAN-CVE-2023-0240, GHSA-rr76-fj9v-7w82, UBUNTU-CVE-2023-0240

## What is CVE-2023-0240?

CVE-2023-0240 is a high-severity use after free vulnerability in Linux kernel, published on 30 Jan 2023. It can only be exploited from the same machine or local network, with no action from the victim.

### Official description

There is a logic error in io_uring's implementation which can be used to trigger a use-after-free vulnerability leading to privilege escalation.

In the io_prep_async_work function the assumption that the last io_grab_identity call cannot return false is not true, and in this case the function will use the init_cred or the previous linked requests identity to do operations instead of using the current identity. This can lead to reference counting issues causing use-after-free. We recommend upgrading past version 5.10.161.

Weakness: CWE-416 (Use After Free)

## Which versions are affected by CVE-2023-0240?

It affects 1 product.


Products: Linux kernel.

## How do I fix CVE-2023-0240?

Upgrade to a fixed version.

## Is CVE-2023-0240 being exploited?

There is no known exploitation of CVE-2023-0240 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-2023-0240 and fix it if it is affected.

What it is: CVE-2023-0240 is a high-severity use after free vulnerability in Linux kernel, published on 30 Jan 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-2023-0240 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-2023-0240/ (Markdown: https://insights.sbomify.com/CVE-2023-0240/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2023-0240
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2023-0240
- OSV: https://osv.dev/vulnerability/CVE-2023-0240

---
From sbomify Insights: https://insights.sbomify.com/CVE-2023-0240/
Summaries are generated and may contain mistakes; the official description above is the record.