# CVE-2023-53825: kcm: Fix error handling for SOCK_DGRAM in kcm_sendmsg().

> A memory leak in the Linux kernel's kcm module can lead to resource exhaustion and denial of service when handling SOCK_DGRAM messages.

- **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-2023-53825, DEBIAN-CVE-2023-53825, GHSA-qqwx-6fr4-mfj2, UBUNTU-CVE-2023-53825

## What is CVE-2023-53825?

CVE-2023-53825 is a memory corruption 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:

kcm: Fix error handling for SOCK_DGRAM in kcm_sendmsg().

syzkaller found a memory leak in kcm_sendmsg(), and commit c821a88bd720
("kcm: Fix memory leak in error path of kcm_sendmsg()") suppressed it by
updating kcm_tx_msg(head)->last_skb if partial data is copied so that the
following sendmsg() will resume from the skb.

However, we cannot know how many bytes were copied when we get the error.
Thus, we could mess up the MSG_MORE queue.

When kcm_sendmsg() fails for SOCK_DGRAM, we should purge the queue as we
do so for UDP by udp_flush_pending_frames().

Even without this change, when the error occurred, the following sendmsg()
resumed from a wrong skb and the queue was messed up.  However, we have
yet to get such a report, and only syzkaller stumbled on it.  So, this
can be changed safely.

Note this does not change SOCK_SEQPACKET behaviour.

## Which versions are affected by CVE-2023-53825?


## How do I fix CVE-2023-53825?

Apply the vendor's patch.

## Is CVE-2023-53825 being exploited?

There is no known exploitation of CVE-2023-53825 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2023-53825 and fix it if it is affected.

What it is: CVE-2023-53825 is a memory corruption 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-2023-53825 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-2023-53825/ (Markdown: https://insights.sbomify.com/CVE-2023-53825/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2023-53825
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2023-53825
- OSV: https://osv.dev/vulnerability/CVE-2023-53825

---
From sbomify Insights: https://insights.sbomify.com/CVE-2023-53825/
Summaries are generated and may contain mistakes; the official description above is the record.