# CVE-2025-39698: io_uring/futex: ensure io_futex_wait() cleans up properly on failure

> A use-after-free vulnerability in the Linux kernel's io_uring futex implementation allows attackers to potentially execute arbitrary code or 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:** 5 Sep 2025
- **Updated:** 5 Aug 2026
- **Also known as:** BELL-CVE-2025-39698, DEBIAN-CVE-2025-39698, GHSA-q7v5-hrgw-5gjh, ROOT-OS-DEBIAN-13-CVE-2025-39698, ROOT-OS-UBUNTU-2404-CVE-2025-39698

## What is CVE-2025-39698?

CVE-2025-39698 is a high-severity use after free vulnerability in Linux kernel, published on 5 Sep 2025. 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/futex: ensure io_futex_wait() cleans up properly on failure

The io_futex_data is allocated upfront and assigned to the io_kiocb
async_data field, but the request isn't marked with REQ_F_ASYNC_DATA
at that point. Those two should always go together, as the flag tells
io_uring whether the field is valid or not.

Additionally, on failure cleanup, the futex handler frees the data but
does not clear ->async_data. Clear the data and the flag in the error
path as well.

Thanks to Trend Micro Zero Day Initiative and particularly ReDress for
reporting this.

Weakness: CWE-416 (Use After Free), CWE-672 (Operation on a Resource after Expiration or Release)

## Which versions are affected by CVE-2025-39698?

It affects 1 product.


Products: Linux kernel.

## How do I fix CVE-2025-39698?

Apply the vendor's patch.

## Is CVE-2025-39698 being exploited?

There is no known exploitation of CVE-2025-39698 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-2025-39698 and fix it if it is affected.

What it is: CVE-2025-39698 is a high-severity use after free vulnerability in Linux kernel, published on 5 Sep 2025. 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-2025-39698 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-2025-39698/ (Markdown: https://insights.sbomify.com/CVE-2025-39698/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2025-39698
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2025-39698
- OSV: https://osv.dev/vulnerability/CVE-2025-39698

---
From sbomify Insights: https://insights.sbomify.com/CVE-2025-39698/
Summaries are generated and may contain mistakes; the official description above is the record.