# CVE-2026-72218: lockd: Plug nlm_file refcount leak on cached nlm_do_fopen() failure

> A refcount leak in the Linux kernel lockd module allows remote attackers to cause a denial of service by exhausting file resources.

- **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:** 15 Aug 2026
- **Updated:** 17 Aug 2026
- **Also known as:** BELL-CVE-2026-72218, DEBIAN-CVE-2026-72218, GHSA-mwwg-vq2v-v2c8, UBUNTU-CVE-2026-72218

## What is CVE-2026-72218?

CVE-2026-72218 is a 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:

lockd: Plug nlm_file refcount leak on cached nlm_do_fopen() failure

The cached-file path in nlm_lookup_file() reaches the found: label
unconditionally, even when nlm_do_fopen() fails. At that label
*result and file->f_count are updated before the error is returned.
The wrappers nlm3svc_lookup_file() and nlm4svc_lookup_file() then
bail out of their switch without copying *result back to their
caller, so the proc handler's local nlm_file pointer remains NULL
and the cleanup path skips nlm_release_file(). The f_count
increment is never released, and nlm_traverse_files() can no
longer reap the file because its refcount never returns to zero
between requests.

Short-circuit the cached path so neither *result nor f_count is
touched when nlm_do_fopen() fails on a hashed nlm_file.

## Which versions are affected by CVE-2026-72218?


## How do I fix CVE-2026-72218?

Apply the vendor's patch.

## Is CVE-2026-72218 being exploited?

There is no known exploitation of CVE-2026-72218 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-72218 and fix it if it is affected.

What it is: CVE-2026-72218 is a 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-2026-72218 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-2026-72218/ (Markdown: https://insights.sbomify.com/CVE-2026-72218/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-72218
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-72218
- OSV: https://osv.dev/vulnerability/CVE-2026-72218

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-72218/
Summaries are generated and may contain mistakes; the official description above is the record.