# CVE-2025-39834: net/mlx5: HWS, Fix memory leak in hws_action_get_shared_stc_nic error flow

> A memory leak in the Linux kernel's mlx5 driver allows attackers to cause denial of service by triggering an error flow with invalid STC types.

- **Severity:** Medium 5.5 (`CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/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:** 16 Sep 2025
- **Updated:** 21 Oct 2026
- **Also known as:** BELL-CVE-2025-39834, DEBIAN-CVE-2025-39834, GHSA-45vc-784v-vp78, ROOT-OS-DEBIAN-13-CVE-2025-39834, UBUNTU-CVE-2025-39834

## What is CVE-2025-39834?

CVE-2025-39834 is a medium-severity denial of service vulnerability in Linux kernel, published on 16 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:

net/mlx5: HWS, Fix memory leak in hws_action_get_shared_stc_nic error flow

When an invalid stc_type is provided, the function allocates memory for
shared_stc but jumps to unlock_and_out without freeing it, causing a
memory leak.

Fix by jumping to free_shared_stc label instead to ensure proper cleanup.

Weakness: CWE-401 (Missing Release of Memory after Effective Lifetime)

## Which versions are affected by CVE-2025-39834?

It affects 1 product.


Products: Linux kernel.

## How do I fix CVE-2025-39834?

Apply the vendor's patch.

## Is CVE-2025-39834 being exploited?

There is no known exploitation of CVE-2025-39834 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-2025-39834 and fix it if it is affected.

What it is: CVE-2025-39834 is a medium-severity denial of service vulnerability in Linux kernel, published on 16 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-2025-39834 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-2025-39834/ (Markdown: https://insights.sbomify.com/CVE-2025-39834/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2025-39834
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2025-39834
- OSV: https://osv.dev/vulnerability/CVE-2025-39834

---
From sbomify Insights: https://insights.sbomify.com/CVE-2025-39834/
Summaries are generated and may contain mistakes; the official description above is the record.