# CVE-2026-46181: RDMA/mlx4: Fix mis-use of RCU in mlx4_srq_event()

> A race condition in the Linux kernel RDMA mlx4 driver can cause a system crash if an event is delivered before initialization completes.

- **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:** 28 May 2026
- **Updated:** 21 Oct 2026
- **Also known as:** AZL-88964, BELL-CVE-2026-46181, DEBIAN-CVE-2026-46181, GHSA-pw2f-xmgc-f22m, ROOT-OS-DEBIAN-11-CVE-2026-46181, ROOT-OS-DEBIAN-12-CVE-2026-46181, ROOT-OS-DEBIAN-13-CVE-2026-46181, ROOT-OS-UBUNTU-2204-CVE-2026-46181, ROOT-OS-UBUNTU-2404-CVE-2026-46181, UBUNTU-CVE-2026-46181

## What is CVE-2026-46181?

CVE-2026-46181 is a high-severity vulnerability in Linux kernel, published on 28 May 2026. 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:

RDMA/mlx4: Fix mis-use of RCU in mlx4_srq_event()

Sashiko points out the radix_tree itself is RCU safe, but nothing ever
frees the mlx4_srq struct with RCU, and it isn't even accessed within the
RCU critical section. It also will crash if an event is delivered before
the srq object is finished initializing.

Use the spinlock since it isn't easy to make RCU work, use
refcount_inc_not_zero() to protect against partially initialized objects,
and order the refcount_set() to be after the srq is fully initialized.

Weakness: CWE-366 (Race Condition within a Thread)

## Which versions are affected by CVE-2026-46181?

It affects 1 product.


Products: Linux kernel.

## How do I fix CVE-2026-46181?

Apply the vendor's patch.

## Is CVE-2026-46181 being exploited?

There is no known exploitation of CVE-2026-46181 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-2026-46181 and fix it if it is affected.

What it is: CVE-2026-46181 is a high-severity vulnerability in Linux kernel, published on 28 May 2026. 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-2026-46181 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-2026-46181/ (Markdown: https://insights.sbomify.com/CVE-2026-46181/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-46181
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-46181
- OSV: https://osv.dev/vulnerability/CVE-2026-46181

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-46181/
Summaries are generated and may contain mistakes; the official description above is the record.