CVE-2023-54276: In the Linux kernel, the following vulnerability has been resolved: nfsd: move init of percpu reply_cache_stats counters back to nfsd_init_net Commi...

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.

Metrics

EPSS Probability

0.17%

6.4th percentile

Probability of exploitation in the next 30 days. Learn more

Affected Software

Source: CNA advisory (CVE.org). NVD analysis pending.

Vendor	Product	Versions
Linux	Linux	>= 4e18b58b106e34ac69d3052dd91f520bd83cf2fc, < 3025d489f9c8984d1bf5916c4a20097ed80fca5c; >= 70fdee548c036c6bdb496f284c9e78f1654b6dd0, < 8549384d0f65981761fe2077d04fa2a8d37b54e0; >= e7e571ed4ec7bb50136233d8e7b986efef2af8c1, < 66a178177b2b3bb1d71e854c5e7bbb320eb0e566; >= f5f9d4a314da88c0a5faa6d168bf69081b7a25ae, < 768c408594b52d8531e1a8ab62e5620c19213e73; >= f5f9d4a314da88c0a5faa6d168bf69081b7a25ae, < ed9ab7346e908496816cffdecd46932035f66e2e
Linux	Linux	6.3

References

Timeline

Published: Dec 30, 2025
Last Modified: Jun 17, 2026
Status: Deferred

Frequently Asked Questions

What is CVE-2023-54276?

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.

How severe is CVE-2023-54276?

Severity scoring for CVE-2023-54276 is pending analysis. The EPSS model estimates a 0.17% probability of exploitation in the next 30 days.

How do I fix CVE-2023-54276?

Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

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