# CVE-2023-54276: nfsd: move init of percpu reply_cache_stats counters back to nfsd_init_net

> An unprivileged local user can cause a kernel crash by reading a specific proc file when the NFS daemon is not started on non-x86_64 architectures.

- **Severity:** Not scored
- **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:** 30 Dec 2025
- **Updated:** 11 May 2026
- **Also known as:** BELL-CVE-2023-54276, DEBIAN-CVE-2023-54276, GHSA-4hqq-5h4g-jhph, UBUNTU-CVE-2023-54276

## What is CVE-2023-54276?

CVE-2023-54276 is a vulnerability in Linux, published on 30 Dec 2025. 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 init of percpu reply_cache_stats counters back to nfsd_init_net

Commit f5f9d4a314da ("nfsd: move reply cache initialization into nfsd
startup") moved the initialization of the reply cache into nfsd startup,
but didn't account for the stats counters, which can be accessed before
nfsd is ever started. The result can be a NULL pointer dereference when
someone accesses /proc/fs/nfsd/reply_cache_stats while nfsd is still
shut down.

This is a regression and a user-triggerable oops in the right situation:

- non-x86_64 arch
- /proc/fs/nfsd is mounted in the namespace
- nfsd is not started in the namespace
- unprivileged user calls "cat /proc/fs/nfsd/reply_cache_stats"

Although this is easy to trigger on some arches (like aarch64), on
x86_64, calling this_cpu_ptr(NULL) evidently returns a pointer to the
fixed_percpu_data. That struct looks just enough like a newly
initialized percpu var to allow nfsd_reply_cache_stats_show to access
it without Oopsing.

Move the initialization of the per-net+per-cpu reply-cache counters
back into nfsd_init_net, while leaving the rest of the reply cache
allocations to be done at nfsd startup time.

Kudos to Eirik who did most of the legwork to track this down.

## Which versions are affected by CVE-2023-54276?


## How do I fix CVE-2023-54276?

Apply the vendor's patch.

## Is CVE-2023-54276 being exploited?

There is no known exploitation of CVE-2023-54276 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2023-54276 and fix it if it is affected.

What it is: CVE-2023-54276 is a vulnerability in Linux, published on 30 Dec 2025. 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-2023-54276 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-2023-54276/ (Markdown: https://insights.sbomify.com/CVE-2023-54276/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2023-54276
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2023-54276
- OSV: https://osv.dev/vulnerability/CVE-2023-54276

---
From sbomify Insights: https://insights.sbomify.com/CVE-2023-54276/
Summaries are generated and may contain mistakes; the official description above is the record.