# CVE-2023-53839: dccp: fix data-race around dp->dccps_mss_cache

> A data race in the Linux kernel DCCP protocol allows attackers to cause a denial of service by triggering inconsistent MSS cache reads.

- **Severity:** Not scored
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 9 Dec 2025
- **Updated:** 11 May 2026
- **Also known as:** BELL-CVE-2023-53839, DEBIAN-CVE-2023-53839, GHSA-8252-q96p-5jpg, UBUNTU-CVE-2023-53839

## What is CVE-2023-53839?

CVE-2023-53839 is a vulnerability in Linux, published on 9 Dec 2025. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

In the Linux kernel, the following vulnerability has been resolved:

dccp: fix data-race around dp->dccps_mss_cache

dccp_sendmsg() reads dp->dccps_mss_cache before locking the socket.
Same thing in do_dccp_getsockopt().

Add READ_ONCE()/WRITE_ONCE() annotations,
and change dccp_sendmsg() to check again dccps_mss_cache
after socket is locked.

## Which versions are affected by CVE-2023-53839?


## How do I fix CVE-2023-53839?

Apply the vendor's patch.

## Is CVE-2023-53839 being exploited?

There is no known exploitation of CVE-2023-53839 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2023-53839 and fix it if it is affected.

What it is: CVE-2023-53839 is a vulnerability in Linux, published on 9 Dec 2025. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2023-53839 in the wild and no public exploit code.

Affected product: Linux. 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-2023-53839/ (Markdown: https://insights.sbomify.com/CVE-2023-53839/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2023-53839
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2023-53839
- OSV: https://osv.dev/vulnerability/CVE-2023-53839

---
From sbomify Insights: https://insights.sbomify.com/CVE-2023-53839/
Summaries are generated and may contain mistakes; the official description above is the record.