# CVE-2026-89485: lockd: pin next file across nlm_inspect_file lock-drop

> A use-after-free vulnerability in the Linux kernel lockd module allows attackers to cause denial of service or potentially execute code via race conditions.

- **Severity:** Critical 9.8 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/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:** 11 Sep 2026
- **Updated:** 19 Oct 2026
- **Also known as:** AZL-100511, BELL-CVE-2026-89485, DEBIAN-CVE-2026-89485, GHSA-wccq-x362-cg9j, UBUNTU-CVE-2026-89485

## What is CVE-2026-89485?

CVE-2026-89485 is a critical use after free 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: pin next file across nlm_inspect_file lock-drop

nlm_traverse_files() pins the current file with f_count++ across
a mutex_unlock for nlm_inspect_file(), but nothing pins the saved
next pointer.  A concurrent nlm_release_file() can kfree the next
file during the unlock window, and the iterator dereferences freed
memory on the next loop step.

Pin both current and next before the lock-drop.  Advance by
swapping the pinned cursors at the end of each iteration so next
is always held alive across the unlock.

Always call nlm_file_release() after dropping the iteration pin,
regardless of whether the file matched the predicate.  Use
nlm_file_inuse(), which does a live walk of the inode lock list,
rather than the cached f_locks field, so skipped files that never
ran nlm_inspect_file() are evaluated correctly.

Because every file in a hash bucket is now pinned and released,
files skipped by the is_failover_file predicate that have no
locks, blocks, shares, or external references are deleted during
traversal.  The old code never evaluated skipped files for
cleanup.  The new behavior is intentional: such files are stale
and should not persist in the table.

## Which versions are affected by CVE-2026-89485?


## How do I fix CVE-2026-89485?

Apply the vendor's patch.

## Is CVE-2026-89485 being exploited?

There is no known exploitation of CVE-2026-89485 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-89485 and fix it if it is affected.

What it is: CVE-2026-89485 is a critical use after free 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-2026-89485 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-2026-89485/ (Markdown: https://insights.sbomify.com/CVE-2026-89485/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-89485
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-89485
- OSV: https://osv.dev/vulnerability/CVE-2026-89485

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-89485/
Summaries are generated and may contain mistakes; the official description above is the record.