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

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.

Sources

• CVE record
• NVD
• OSV
• GitHub advisory
• How this page is made

Also known as BELL-CVE-2023-54276, DEBIAN-CVE-2023-54276, GHSA-4hqq-5h4g-jhph, UBUNTU-CVE-2023-54276.