Vulnerability-Lookup

GHSA-36MF-R537-F6C6

Vulnerability from github – Published: 2026-09-11 21:31 – Updated: 2026-09-14 15:32

Details

In the Linux kernel, the following vulnerability has been resolved:

nfsd: add fh_want_write() for early-verified SETATTR in nfsd_proc_setattr()

The BOTH_TIME_SET branch calls fh_verify() early so setattr_prepare() can inspect the dentry. This causes nfsd_setattr() to skip fh_want_write(), so notify_change() runs without a mount write reference.

Add the missing fh_want_write() call after the early fh_verify().

Severity

9.1 (Critical)


                  
                    CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:H

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{
  "affected": [],
  "aliases": [
    "CVE-2026-89697"
  ],
  "database_specific": {
    "cwe_ids": [],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2026-09-11T20:19:56Z",
    "severity": "CRITICAL"
  },
  "details": "In the Linux kernel, the following vulnerability has been resolved:\n\nnfsd: add fh_want_write() for early-verified SETATTR in nfsd_proc_setattr()\n\nThe BOTH_TIME_SET branch calls fh_verify() early so setattr_prepare()\ncan inspect the dentry. This causes nfsd_setattr() to skip\nfh_want_write(), so notify_change() runs without a mount write\nreference.\n\nAdd the missing fh_want_write() call after the early fh_verify().",
  "id": "GHSA-36mf-r537-f6c6",
  "modified": "2026-09-14T15:32:34Z",
  "published": "2026-09-11T21:31:37Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-89697"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/15ca3b64a69caa6194bed8f98a20ed90a11c11dd"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/2150305134889fb2fc25228d35353bd2f6f29500"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/3eec9d791968c177a4a8cda9af5c04f79dae09cb"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/4e475be769aa9f7a2c1ce55a2b8592cfccacddcc"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/533964d420d385e11b08dd4c56c66ef5dcccaf08"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/9229d824b938f4fb0ea7a5dddade51735e6fe6f9"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/c4a409b86a92815181a8e9395c6bf1696ad19175"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/d823bf9285cdf4514873b85ab5a888878dd4e8f4"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:H",
      "type": "CVSS_V3"
    }
  ]
}

CVE-2026-89697 (GCVE-0-2026-89697)

Vulnerability from cvelistv5 – Published: 2026-09-11 19:46 – Updated: 2026-09-14 12:02

Title

nfsd: add fh_want_write() for early-verified SETATTR in nfsd_proc_setattr()

Summary

In the Linux kernel, the following vulnerability has been resolved: nfsd: add fh_want_write() for early-verified SETATTR in nfsd_proc_setattr() The BOTH_TIME_SET branch calls fh_verify() early so setattr_prepare() can inspect the dentry. This causes nfsd_setattr() to skip fh_want_write(), so notify_change() runs without a mount write reference. Add the missing fh_want_write() call after the early fh_verify().

Severity

9.1 (Critical)


                        
                          CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:H

Assigner

Linux mitre root

References

8 references

URL	Tags
https://git.kernel.org/stable/c/3eec9d791968c177a…
https://git.kernel.org/stable/c/9229d824b938f4fb0…
https://git.kernel.org/stable/c/2150305134889fb2f…
https://git.kernel.org/stable/c/d823bf9285cdf4514…
https://git.kernel.org/stable/c/15ca3b64a69caa619…
https://git.kernel.org/stable/c/533964d420d385e11…
https://git.kernel.org/stable/c/c4a409b86a9281518…
https://git.kernel.org/stable/c/4e475be769aa9f7a2…

Impacted products

2 products

Vendor	Product	Version
Linux	Linux	Affected: cc265089ce1b176dde963c74b53593446ee7f99a , < 3eec9d791968c177a4a8cda9af5c04f79dae09cb (git) Affected: cc265089ce1b176dde963c74b53593446ee7f99a , < 9229d824b938f4fb0ea7a5dddade51735e6fe6f9 (git) Affected: cc265089ce1b176dde963c74b53593446ee7f99a , < 2150305134889fb2fc25228d35353bd2f6f29500 (git) Affected: cc265089ce1b176dde963c74b53593446ee7f99a , < d823bf9285cdf4514873b85ab5a888878dd4e8f4 (git) Affected: cc265089ce1b176dde963c74b53593446ee7f99a , < 15ca3b64a69caa6194bed8f98a20ed90a11c11dd (git) Affected: cc265089ce1b176dde963c74b53593446ee7f99a , < 533964d420d385e11b08dd4c56c66ef5dcccaf08 (git) Affected: cc265089ce1b176dde963c74b53593446ee7f99a , < c4a409b86a92815181a8e9395c6bf1696ad19175 (git) Affected: cc265089ce1b176dde963c74b53593446ee7f99a , < 4e475be769aa9f7a2c1ce55a2b8592cfccacddcc (git) Affected: 1cb57d81cf20fe24b9e2e1daf57bfbdc24b77cd8 (git) Affected: 3.18.46 , < 3.19 (semver)
Linux	Linux	Affected: 4.2 Unaffected: 0 , < 4.2 (semver) Unaffected: 5.10.270 , ≤ 5.10.* (semver) Unaffected: 5.15.221 , ≤ 5.15.* (semver) Unaffected: 6.1.188 , ≤ 6.1.* (semver) Unaffected: 6.6.157 , ≤ 6.6.* (semver) Unaffected: 6.12.109 , ≤ 6.12.* (semver) Unaffected: 6.18.50 , ≤ 6.18.* (semver) Unaffected: 7.2.4 , ≤ 7.2.* (semver) Unaffected: 7.3-rc1 , ≤ * (original_commit_for_fix)

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{
  "containers": {
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "fs/nfsd/nfsproc.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "lessThan": "3eec9d791968c177a4a8cda9af5c04f79dae09cb",
              "status": "affected",
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              "versionType": "git"
            },
            {
              "lessThan": "9229d824b938f4fb0ea7a5dddade51735e6fe6f9",
              "status": "affected",
              "version": "cc265089ce1b176dde963c74b53593446ee7f99a",
              "versionType": "git"
            },
            {
              "lessThan": "2150305134889fb2fc25228d35353bd2f6f29500",
              "status": "affected",
              "version": "cc265089ce1b176dde963c74b53593446ee7f99a",
              "versionType": "git"
            },
            {
              "lessThan": "d823bf9285cdf4514873b85ab5a888878dd4e8f4",
              "status": "affected",
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              "versionType": "git"
            },
            {
              "lessThan": "15ca3b64a69caa6194bed8f98a20ed90a11c11dd",
              "status": "affected",
              "version": "cc265089ce1b176dde963c74b53593446ee7f99a",
              "versionType": "git"
            },
            {
              "lessThan": "533964d420d385e11b08dd4c56c66ef5dcccaf08",
              "status": "affected",
              "version": "cc265089ce1b176dde963c74b53593446ee7f99a",
              "versionType": "git"
            },
            {
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              "versionType": "git"
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              "versionType": "git"
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              "version": "1cb57d81cf20fe24b9e2e1daf57bfbdc24b77cd8",
              "versionType": "git"
            },
            {
              "lessThan": "3.19",
              "status": "affected",
              "version": "3.18.46",
              "versionType": "semver"
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        },
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          "programFiles": [
            "fs/nfsd/nfsproc.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "4.2"
            },
            {
              "lessThan": "4.2",
              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "5.10.*",
              "status": "unaffected",
              "version": "5.10.270",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "5.15.*",
              "status": "unaffected",
              "version": "5.15.221",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.1.*",
              "status": "unaffected",
              "version": "6.1.188",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.6.*",
              "status": "unaffected",
              "version": "6.6.157",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.12.*",
              "status": "unaffected",
              "version": "6.12.109",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.18.*",
              "status": "unaffected",
              "version": "6.18.50",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "7.2.*",
              "status": "unaffected",
              "version": "7.2.4",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "7.3-rc1",
              "versionType": "original_commit_for_fix"
            }
          ]
        }
      ],
      "cpeApplicability": [
        {
          "nodes": [
            {
              "cpeMatch": [
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "5.10.270",
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                },
                {
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                  "versionEndExcluding": "5.15.221",
                  "versionStartIncluding": "4.2",
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                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.1.188",
                  "versionStartIncluding": "4.2",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.6.157",
                  "versionStartIncluding": "4.2",
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                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.12.109",
                  "versionStartIncluding": "4.2",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.18.50",
                  "versionStartIncluding": "4.2",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "7.2.4",
                  "versionStartIncluding": "4.2",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
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                  "versionStartIncluding": "4.2",
                  "vulnerable": true
                },
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          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nnfsd: add fh_want_write() for early-verified SETATTR in nfsd_proc_setattr()\n\nThe BOTH_TIME_SET branch calls fh_verify() early so setattr_prepare()\ncan inspect the dentry. This causes nfsd_setattr() to skip\nfh_want_write(), so notify_change() runs without a mount write\nreference.\n\nAdd the missing fh_want_write() call after the early fh_verify()."
        }
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            "baseSeverity": "CRITICAL",
            "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:H",
            "version": "3.1"
          },
          "scenarios": [
            {
              "lang": "en",
              "value": "AV:N - The bug is in nfsd_proc_setattr(), the in-kernel NFSv2 SETATTR handler. A remote client reaches it by sending an NFSv2 SETATTR RPC over TCP/UDP port 2049 with both atime and mtime set, so no local access to the server is required.\nAC:L - Crafting SETATTR with ATTR_ATIME_SET|ATTR_MTIME_SET and equal timestamps deterministically takes the early fh_verify() path so nfsd_setattr() skips fh_want_write(). The attacker fully controls the RPC; no race or uninfluenced memory layout is required.\nPR:N - Default nfsd exports accept AUTH_SYS and AUTH_NULL with no cryptographic authentication, so the client asserts uid/gid. Any host permitted by the export list can issue SETATTR; this matches prior nfsd CNA scoring as PR:N.\nUI:N - The attacking NFS client issues the SETATTR RPC itself. No administrator or end-user action on the server is required.\nS:U - notify_change() without a mount write reference affects only the exported filesystem in the same kernel security authority. No VM, IOMMU, or sandbox boundary is crossed.\nC:N - The defect is a missing mnt_want_write()/sb_start_write() around notify_change() and commit_metadata(). It does not leak kernel memory, pointers, or file contents beyond ordinary authorized NFS access.\nI:H - nfsd_permission\u0027s read-only check does not cover freeze state, so SETATTR including ATTR_SIZE truncate, mode, and ownership updates proceeds on a frozen export and in a remount-ro race, letting a client mutate files and corrupt snapshots when writes should be blocked.\nA:H - Skipping freeze protection lets setattr run during fsfreeze, which can deadlock (inode_lock versus sb_start_write ordering), trigger filesystem withdraw/asserts such as GFS2 adding buffers while frozen, and hang or crash the nfsd thread."
            }
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        }
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      "providerMetadata": {
        "dateUpdated": "2026-09-14T12:02:04.273Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
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        {
          "url": "https://git.kernel.org/stable/c/c4a409b86a92815181a8e9395c6bf1696ad19175"
        },
        {
          "url": "https://git.kernel.org/stable/c/4e475be769aa9f7a2c1ce55a2b8592cfccacddcc"
        }
      ],
      "title": "nfsd: add fh_want_write() for early-verified SETATTR in nfsd_proc_setattr()",
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        "engine": "bippy-1.2.0"
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  "cveMetadata": {
    "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
    "assignerShortName": "Linux",
    "cveId": "CVE-2026-89697",
    "datePublished": "2026-09-11T19:46:15.772Z",
    "dateReserved": "2026-09-11T19:38:34.750Z",
    "dateUpdated": "2026-09-14T12:02:04.273Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}

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.

Detection rules are retrieved from Rulezet.

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.

Action not permitted

GHSA-36MF-R537-F6C6

CVE-2026-89697 (GCVE-0-2026-89697)

Tags

Sightings

Nomenclature