# CVE-2026-89484: lockd: fix NULL dereference on lockowner allocation failure

> A remote attacker can cause a kernel crash via a null pointer dereference in the lockd module when lockowner allocation fails.

- **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:** 11 Sep 2026
- **Updated:** 21 Oct 2026
- **Also known as:** AZL-100778, BELL-CVE-2026-89484, DEBIAN-CVE-2026-89484, GHSA-7hg8-pf72-7jmh, UBUNTU-CVE-2026-89484

## What is CVE-2026-89484?

CVE-2026-89484 is a vulnerability in Linux, published on 11 Sep 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:

lockd: fix NULL dereference on lockowner allocation failure

nlmclnt_locks_init_private() installs NLM file lock operations even when
nlmclnt_find_lockowner() fails to allocate a lockowner. nlmclnt_proc()
then returns -ENOMEM, but the VFS still tears down the partially
initialized file_lock and calls locks_release_private().

That invokes nlmclnt_locks_release_private(), which dereferences
fl->fl_u.nfs_fl.owner and crashes because the owner was never installed.

Clear fl_ops before attempting to initialize the NLM private state, and
install the NLM lock operations only after a lockowner has been allocated
successfully.

## Which versions are affected by CVE-2026-89484?


## How do I fix CVE-2026-89484?

Apply the vendor's patch.

## Is CVE-2026-89484 being exploited?

There is no known exploitation of CVE-2026-89484 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-89484 and fix it if it is affected.

What it is: CVE-2026-89484 is a vulnerability in Linux, published on 11 Sep 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-2026-89484 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-2026-89484/ (Markdown: https://insights.sbomify.com/CVE-2026-89484/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-89484
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-89484
- OSV: https://osv.dev/vulnerability/CVE-2026-89484

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-89484/
Summaries are generated and may contain mistakes; the official description above is the record.