# CVE-2025-71090: nfsd: fix nfsd_file reference leak in nfsd4_add_rdaccess_to_wrdeleg()

> A reference leak in the Linux kernel NFS server can cause a kernel panic during shutdown, leading to denial of service.

- **Severity:** High 7.5 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/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:** 13 Jan 2026
- **Updated:** 5 Aug 2026
- **Also known as:** BELL-CVE-2025-71090, DEBIAN-CVE-2025-71090, GHSA-p238-x8fg-rqhx, UBUNTU-CVE-2025-71090

## What is CVE-2025-71090?

CVE-2025-71090 is a high-severity denial of service vulnerability in Linux kernel, published on 13 Jan 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:

nfsd: fix nfsd_file reference leak in nfsd4_add_rdaccess_to_wrdeleg()

nfsd4_add_rdaccess_to_wrdeleg() unconditionally overwrites
fp->fi_fds[O_RDONLY] with a newly acquired nfsd_file. However, if
the client already has a SHARE_ACCESS_READ open from a previous OPEN
operation, this action overwrites the existing pointer without
releasing its reference, orphaning the previous reference.

Additionally, the function originally stored the same nfsd_file
pointer in both fp->fi_fds[O_RDONLY] and fp->fi_rdeleg_file with
only a single reference. When put_deleg_file() runs, it clears
fi_rdeleg_file and calls nfs4_file_put_access() to release the file.

However, nfs4_file_put_access() only releases fi_fds[O_RDONLY] when
the fi_access[O_RDONLY] counter drops to zero. If another READ open
exists on the file, the counter remains elevated and the nfsd_file
reference from the delegation is never released. This potentially
causes open conflicts on that file.

Then, on server shutdown, these leaks cause __nfsd_file_cache_purge()
to encounter files with an elevated reference count that cannot be
cleaned up, ultimately triggering a BUG() in kmem_cache_destroy()
because there are still nfsd_file objects allocated in that cache.

## Which versions are affected by CVE-2025-71090?

It affects 1 product.


Products: Linux kernel.

## How do I fix CVE-2025-71090?

Apply the vendor's patch.

## Is CVE-2025-71090 being exploited?

There is no known exploitation of CVE-2025-71090 in the wild and no public exploit code.

## Other vulnerabilities in Linux kernel

- [CVE-2026-53266](https://insights.sbomify.com/CVE-2026-53266/): Linux Kernel Out-of-Bounds Write (high 8.8, exploited in the wild)
- [CVE-2013-6282](https://insights.sbomify.com/CVE-2013-6282/): Linux Kernel Improper Input Validation (high 8.8, exploited in the wild)
- [CVE-2022-0185](https://insights.sbomify.com/CVE-2022-0185/): Linux Kernel Heap-Based Buffer Overflow (high 8.4, exploited in the wild)
- [CVE-2013-2094](https://insights.sbomify.com/CVE-2013-2094/): Linux Kernel Privilege Escalation (high 8.4, exploited in the wild)
- [CVE-2026-53362](https://insights.sbomify.com/CVE-2026-53362/): Linux Kernel Unspecified (high 7.8, exploited in the wild)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2025-71090 and fix it if it is affected.

What it is: CVE-2025-71090 is a high-severity denial of service vulnerability in Linux kernel, published on 13 Jan 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-2025-71090 in the wild and no public exploit code.

Affected product: Linux kernel. 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-2025-71090/ (Markdown: https://insights.sbomify.com/CVE-2025-71090/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2025-71090
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2025-71090
- OSV: https://osv.dev/vulnerability/CVE-2025-71090

---
From sbomify Insights: https://insights.sbomify.com/CVE-2025-71090/
Summaries are generated and may contain mistakes; the official description above is the record.