# CVE-2026-74396: RDMA/mlx5: Fix UMR XLT cleanup on ODP populate failure

> A resource leak and mutex lock issue in the Linux kernel RDMA driver can cause denial of service when ODP populate fails.

- **Severity:** High 7.5 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 15 Aug 2026
- **Updated:** 16 Oct 2026
- **Also known as:** BELL-CVE-2026-74396, DEBIAN-CVE-2026-74396, GHSA-2vqx-xvhw-m854, UBUNTU-CVE-2026-74396

## What is CVE-2026-74396?

CVE-2026-74396 is a high-severity denial of service vulnerability in Linux, published on 15 Aug 2026. 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:

RDMA/mlx5: Fix UMR XLT cleanup on ODP populate failure

mlx5r_umr_update_xlt() allocates and DMA maps an XLT buffer with
mlx5r_umr_create_xlt(). The buffer is released by the common cleanup path
through mlx5r_umr_unmap_free_xlt().

After mlx5_odp_populate_xlt() became fallible, its error path returned
directly and skipped that cleanup. This leaks the XLT DMA mapping and
buffer. If the emergency XLT page was used, it also leaves
xlt_emergency_page_mutex locked.

Break out of the loop so execution falls through the existing cleanup path.

## Which versions are affected by CVE-2026-74396?


## How do I fix CVE-2026-74396?

Apply the vendor's patch.

## Is CVE-2026-74396 being exploited?

There is no known exploitation of CVE-2026-74396 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-74396 and fix it if it is affected.

What it is: CVE-2026-74396 is a high-severity denial of service vulnerability in Linux, published on 15 Aug 2026. 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-2026-74396 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-2026-74396/ (Markdown: https://insights.sbomify.com/CVE-2026-74396/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-74396
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-74396
- OSV: https://osv.dev/vulnerability/CVE-2026-74396

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-74396/
Summaries are generated and may contain mistakes; the official description above is the record.