# CVE-2026-89668: nfsd: move nfsd_debugfs_init() after nfsd4_init_slabs() in init_nfsd()

> A use-after-free vulnerability in the Linux kernel NFS server allows attackers to execute arbitrary code or cause a denial of service via stale debugfs pointers.

- **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:** 11 Sep 2026
- **Updated:** 19 Oct 2026
- **Also known as:** BELL-CVE-2026-89668, DEBIAN-CVE-2026-89668, GHSA-9vcc-j8g4-f8ff, UBUNTU-CVE-2026-89668

## What is CVE-2026-89668?

CVE-2026-89668 is a high-severity use after free 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:

nfsd: move nfsd_debugfs_init() after nfsd4_init_slabs() in init_nfsd()

nfsd_debugfs_init() runs before nfsd4_init_slabs() in init_nfsd().
If the slab allocation fails, the bare "return retval" bypasses
nfsd_debugfs_exit(), leaving orphan debugfs files with stale fops
pointers into the freed module text.

Move nfsd_debugfs_init() to after the slab init succeeds, so the
early return has no debugfs state to clean up.

Since debugfs is now the more recently initialized of the two, also
update the unwind paths to match reverse-initialization (LIFO) order:
run nfsd_debugfs_exit() before nfsd4_free_slabs() in both the
init_nfsd() error path and exit_nfsd(). The nfsd debugfs files only
reference module-global state and have no dependency on the slab
caches, so that reordering is a cleanup with no functional change.

## Which versions are affected by CVE-2026-89668?


## How do I fix CVE-2026-89668?

Apply the vendor's patch.

## Is CVE-2026-89668 being exploited?

There is no known exploitation of CVE-2026-89668 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-89668 and fix it if it is affected.

What it is: CVE-2026-89668 is a high-severity use after free 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-2026-89668 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-2026-89668/ (Markdown: https://insights.sbomify.com/CVE-2026-89668/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-89668
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-89668
- OSV: https://osv.dev/vulnerability/CVE-2026-89668

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-89668/
Summaries are generated and may contain mistakes; the official description above is the record.