# CVE-2026-89505: RDMA/uverbs: Guard legacy bundles without method_elm

> A null pointer dereference in the Linux kernel RDMA subsystem allows local attackers to cause a denial of service via malformed provider input.

- **Severity:** Not scored
- **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:** 11 Sep 2026
- **Updated:** 19 Oct 2026
- **Also known as:** DEBIAN-CVE-2026-89505, GHSA-6frh-mf5h-mgw9, UBUNTU-CVE-2026-89505

## What is CVE-2026-89505?

CVE-2026-89505 is a vulnerability in Linux, published on 11 Sep 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/uverbs: Guard legacy bundles without method_elm

The legacy write() path dispatches through a uverbs_api_write_method, but
the uverbs_attr_bundle passed to provider code does not have an ioctl
method element. If malformed provider input causes the common uverbs
validation code to emit an error message, uverbs_get_handler_fn()
dereferences the uninitialized method_elm pointer.

Initialize method_elm explicitly for legacy bundles and make
uverbs_get_handler_fn() return NULL when no ioctl method is present. The
legacy dispatcher continues to use its local write method, while the ioctl
path continues to use the registered ioctl handler.

## Which versions are affected by CVE-2026-89505?


## How do I fix CVE-2026-89505?

Apply the vendor's patch.

## Is CVE-2026-89505 being exploited?

There is no known exploitation of CVE-2026-89505 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-89505 and fix it if it is affected.

What it is: CVE-2026-89505 is a vulnerability in Linux, published on 11 Sep 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-2026-89505 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-2026-89505/ (Markdown: https://insights.sbomify.com/CVE-2026-89505/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-89505
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-89505
- OSV: https://osv.dev/vulnerability/CVE-2026-89505

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-89505/
Summaries are generated and may contain mistakes; the official description above is the record.