Vulnerability-Lookup

GHSA-4HQQ-5H4G-JHPH

Vulnerability from github – Published: 2025-12-30 15:30 – Updated: 2025-12-30 15:30

Details

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.

Show details on source website

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{
  "affected": [],
  "aliases": [
    "CVE-2023-54276"
  ],
  "database_specific": {
    "cwe_ids": [],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2025-12-30T13:16:16Z",
    "severity": null
  },
  "details": "In the Linux kernel, the following vulnerability has been resolved:\n\nnfsd: move init of percpu reply_cache_stats counters back to nfsd_init_net\n\nCommit f5f9d4a314da (\"nfsd: move reply cache initialization into nfsd\nstartup\") moved the initialization of the reply cache into nfsd startup,\nbut didn\u0027t account for the stats counters, which can be accessed before\nnfsd is ever started. The result can be a NULL pointer dereference when\nsomeone accesses /proc/fs/nfsd/reply_cache_stats while nfsd is still\nshut down.\n\nThis is a regression and a user-triggerable oops in the right situation:\n\n- non-x86_64 arch\n- /proc/fs/nfsd is mounted in the namespace\n- nfsd is not started in the namespace\n- unprivileged user calls \"cat /proc/fs/nfsd/reply_cache_stats\"\n\nAlthough this is easy to trigger on some arches (like aarch64), on\nx86_64, calling this_cpu_ptr(NULL) evidently returns a pointer to the\nfixed_percpu_data. That struct looks just enough like a newly\ninitialized percpu var to allow nfsd_reply_cache_stats_show to access\nit without Oopsing.\n\nMove the initialization of the per-net+per-cpu reply-cache counters\nback into nfsd_init_net, while leaving the rest of the reply cache\nallocations to be done at nfsd startup time.\n\nKudos to Eirik who did most of the legwork to track this down.",
  "id": "GHSA-4hqq-5h4g-jhph",
  "modified": "2025-12-30T15:30:34Z",
  "published": "2025-12-30T15:30:34Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2023-54276"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/3025d489f9c8984d1bf5916c4a20097ed80fca5c"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/66a178177b2b3bb1d71e854c5e7bbb320eb0e566"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/768c408594b52d8531e1a8ab62e5620c19213e73"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/8549384d0f65981761fe2077d04fa2a8d37b54e0"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/ed9ab7346e908496816cffdecd46932035f66e2e"
    }
  ],
  "schema_version": "1.4.0",
  "severity": []
}

CVE-2023-54276 (GCVE-0-2023-54276)

Vulnerability from cvelistv5 – Published: 2025-12-30 12:16 – Updated: 2026-05-11 19:58

Title

nfsd: move init of percpu reply_cache_stats counters back to nfsd_init_net

Summary

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.

Severity

No CVSS data available.

Assigner

Linux CNA under the mitre root

CNA scorecard D 53/100 over 6641 records in the last 180 days details

References

5 references

URL	Tags
https://git.kernel.org/stable/c/3025d489f9c8984d1…
https://git.kernel.org/stable/c/8549384d0f6598176…
https://git.kernel.org/stable/c/66a178177b2b3bb1d…
https://git.kernel.org/stable/c/768c408594b52d853…
https://git.kernel.org/stable/c/ed9ab7346e9084968…

Impacted products

2 products

Vendor	Product	Version
Linux	Linux	Affected: 4e18b58b106e34ac69d3052dd91f520bd83cf2fc , < 3025d489f9c8984d1bf5916c4a20097ed80fca5c (git) Affected: 70fdee548c036c6bdb496f284c9e78f1654b6dd0 , < 8549384d0f65981761fe2077d04fa2a8d37b54e0 (git) Affected: e7e571ed4ec7bb50136233d8e7b986efef2af8c1 , < 66a178177b2b3bb1d71e854c5e7bbb320eb0e566 (git) Affected: f5f9d4a314da88c0a5faa6d168bf69081b7a25ae , < 768c408594b52d8531e1a8ab62e5620c19213e73 (git) Affected: f5f9d4a314da88c0a5faa6d168bf69081b7a25ae , < ed9ab7346e908496816cffdecd46932035f66e2e (git)
Linux	Linux	Affected: 6.3 Unaffected: 0 , < 6.3 (semver) Unaffected: 6.4.4 , ≤ 6.4.* (semver) Unaffected: 6.5 , ≤ * (original_commit_for_fix)

Show details on NVD website

JSON

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{
  "containers": {
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "fs/nfsd/cache.h",
            "fs/nfsd/nfscache.c",
            "fs/nfsd/nfsctl.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
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              "status": "affected",
              "version": "4e18b58b106e34ac69d3052dd91f520bd83cf2fc",
              "versionType": "git"
            },
            {
              "lessThan": "8549384d0f65981761fe2077d04fa2a8d37b54e0",
              "status": "affected",
              "version": "70fdee548c036c6bdb496f284c9e78f1654b6dd0",
              "versionType": "git"
            },
            {
              "lessThan": "66a178177b2b3bb1d71e854c5e7bbb320eb0e566",
              "status": "affected",
              "version": "e7e571ed4ec7bb50136233d8e7b986efef2af8c1",
              "versionType": "git"
            },
            {
              "lessThan": "768c408594b52d8531e1a8ab62e5620c19213e73",
              "status": "affected",
              "version": "f5f9d4a314da88c0a5faa6d168bf69081b7a25ae",
              "versionType": "git"
            },
            {
              "lessThan": "ed9ab7346e908496816cffdecd46932035f66e2e",
              "status": "affected",
              "version": "f5f9d4a314da88c0a5faa6d168bf69081b7a25ae",
              "versionType": "git"
            }
          ]
        },
        {
          "defaultStatus": "affected",
          "product": "Linux",
          "programFiles": [
            "fs/nfsd/cache.h",
            "fs/nfsd/nfscache.c",
            "fs/nfsd/nfsctl.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "6.3"
            },
            {
              "lessThan": "6.3",
              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.4.*",
              "status": "unaffected",
              "version": "6.4.4",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "6.5",
              "versionType": "original_commit_for_fix"
            }
          ]
        }
      ],
      "cpeApplicability": [
        {
          "nodes": [
            {
              "cpeMatch": [
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.4.4",
                  "versionStartIncluding": "6.3",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.5",
                  "versionStartIncluding": "6.3",
                  "vulnerable": true
                }
              ],
              "negate": false,
              "operator": "OR"
            }
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        }
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      "descriptions": [
        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nnfsd: move init of percpu reply_cache_stats counters back to nfsd_init_net\n\nCommit f5f9d4a314da (\"nfsd: move reply cache initialization into nfsd\nstartup\") moved the initialization of the reply cache into nfsd startup,\nbut didn\u0027t account for the stats counters, which can be accessed before\nnfsd is ever started. The result can be a NULL pointer dereference when\nsomeone accesses /proc/fs/nfsd/reply_cache_stats while nfsd is still\nshut down.\n\nThis is a regression and a user-triggerable oops in the right situation:\n\n- non-x86_64 arch\n- /proc/fs/nfsd is mounted in the namespace\n- nfsd is not started in the namespace\n- unprivileged user calls \"cat /proc/fs/nfsd/reply_cache_stats\"\n\nAlthough this is easy to trigger on some arches (like aarch64), on\nx86_64, calling this_cpu_ptr(NULL) evidently returns a pointer to the\nfixed_percpu_data. That struct looks just enough like a newly\ninitialized percpu var to allow nfsd_reply_cache_stats_show to access\nit without Oopsing.\n\nMove the initialization of the per-net+per-cpu reply-cache counters\nback into nfsd_init_net, while leaving the rest of the reply cache\nallocations to be done at nfsd startup time.\n\nKudos to Eirik who did most of the legwork to track this down."
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-05-11T19:58:50.629Z",
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        "shortName": "Linux"
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        },
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        },
        {
          "url": "https://git.kernel.org/stable/c/ed9ab7346e908496816cffdecd46932035f66e2e"
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      ],
      "title": "nfsd: move init of percpu reply_cache_stats counters back to nfsd_init_net",
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    "datePublished": "2025-12-30T12:16:05.020Z",
    "dateReserved": "2025-12-30T12:06:44.523Z",
    "dateUpdated": "2026-05-11T19:58:50.629Z",
    "state": "PUBLISHED"
  },
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}

Sightings

Author	Source	Type	Date	Other

Nomenclature

Seen: The vulnerability was mentioned, discussed, or observed by the user.
Confirmed: The vulnerability has been validated from an analyst's perspective.
Published Proof of Concept: A public proof of concept is available for this vulnerability.
Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
Not confirmed: The user expressed doubt about the validity of the vulnerability.
Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.

Vulnerability timeline

Sightings and recorded dates, grouped by day · UTC

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How durations are calculated

Following the VTEM framework (Black Hat USA 2015), time to patch starts when the vendor or a coordinator was informed, total time to patch at discovery, and disclosure to patch at public disclosure; vendor response time runs from the report to its acknowledgement. Time to exploit and time unpatched start at the earliest discovery or report, falling back to public disclosure. Unpatched time ends at the first recorded patch, or the calculation time when no patch is recorded. Exploitation to patch shows the interval between those two events; a published proof of concept is a public exploit, not exploitation.

Each result shows its source dates. A negative interval means the end event came first; when date-only inputs leave the order open, the result says so. Date-only inputs are approximate. The earliest evidence wins: KEV report dates and sightings are labelled as such. Records describing another vulnerability are listed but never calculated from, and a PoC alone does not establish exploitation. Missing patch evidence does not prove that no patch exists. Filters below change the event list only.

Publication & reservation Sightings KEV catalogs Other timestamps

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The MITRE ATT&CK techniques below are AI-generated suggestions, inferred from the description of the vulnerability by the CIRCL/vulnerability-attack-technique-classification-roberta-base model, served locally by ML-Gateway. They have not been verified by an analyst and are provided for guidance only.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
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