Vulnerability-Lookup

GHSA-MR23-3FXM-CW86

Vulnerability from github – Published: 2026-09-11 21:31 – Updated: 2026-09-13 09:32

Details

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

NFSD: Prevent client use-after-free during NFSv4.0 revoked-state cleanup

nfs40_clean_admin_revoked() takes a stateid reference under clp->cl_lock, drops nn->client_lock, and calls nfsd4_drop_revoked_stid(), which dereferences the stateid's client through s->sc_client->cl_lock. The stateid reference does not pin the client, so a teardown racing the dropped lock can free the client while nfsd4_drop_revoked_stid() is still using it.

This cleanup runs from the laundromat, so a periodic sweep can race force_expire_client() driven by a write to the clients//ctl file.

Skip a client that is already expiring and otherwise pin it with cl_rpc_users under client_lock before dropping the lock, matching nfsd4_revoke_states().

Severity

9.8 (Critical)


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

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{
  "affected": [],
  "aliases": [
    "CVE-2026-89658"
  ],
  "database_specific": {
    "cwe_ids": [],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2026-09-11T20:19:52Z",
    "severity": "CRITICAL"
  },
  "details": "In the Linux kernel, the following vulnerability has been resolved:\n\nNFSD: Prevent client use-after-free during NFSv4.0 revoked-state cleanup\n\nnfs40_clean_admin_revoked() takes a stateid reference under\nclp-\u003ecl_lock, drops nn-\u003eclient_lock, and calls\nnfsd4_drop_revoked_stid(), which dereferences the stateid\u0027s client\nthrough s-\u003esc_client-\u003ecl_lock.  The stateid reference does not pin the\nclient, so a teardown racing the dropped lock can free the client\nwhile nfsd4_drop_revoked_stid() is still using it.\n\nThis cleanup runs from the laundromat, so a periodic sweep can race\nforce_expire_client() driven by a write to the clients/\u003cid\u003e/ctl file.\n\nSkip a client that is already expiring and otherwise pin it with\ncl_rpc_users under client_lock before dropping the lock, matching\nnfsd4_revoke_states().",
  "id": "GHSA-mr23-3fxm-cw86",
  "modified": "2026-09-13T09:32:26Z",
  "published": "2026-09-11T21:31:35Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-89658"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/0ae0d2b5c5a1b39c0b3c15d96b32a5b0c583d519"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/7b4f8a1586c42d3afc3c0ac779af2db7ab1a5c55"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/81cf7f1413862f87b078920c838460a6a88aa030"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/b413ec5b23e3445dc9c4f273116078e2d4747626"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H",
      "type": "CVSS_V3"
    }
  ]
}

CVE-2026-89658 (GCVE-0-2026-89658)

Vulnerability from cvelistv5 – Published: 2026-09-11 19:45 – Updated: 2026-09-13 06:32

Title

NFSD: Prevent client use-after-free during NFSv4.0 revoked-state cleanup

Summary

In the Linux kernel, the following vulnerability has been resolved: NFSD: Prevent client use-after-free during NFSv4.0 revoked-state cleanup nfs40_clean_admin_revoked() takes a stateid reference under clp->cl_lock, drops nn->client_lock, and calls nfsd4_drop_revoked_stid(), which dereferences the stateid's client through s->sc_client->cl_lock. The stateid reference does not pin the client, so a teardown racing the dropped lock can free the client while nfsd4_drop_revoked_stid() is still using it. This cleanup runs from the laundromat, so a periodic sweep can race force_expire_client() driven by a write to the clients/<id>/ctl file. Skip a client that is already expiring and otherwise pin it with cl_rpc_users under client_lock before dropping the lock, matching nfsd4_revoke_states().

Severity

9.8 (Critical)


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

Assigner

Linux mitre root

References

4 references

URL	Tags
https://git.kernel.org/stable/c/0ae0d2b5c5a1b39c0…
https://git.kernel.org/stable/c/b413ec5b23e3445dc…
https://git.kernel.org/stable/c/81cf7f1413862f87b…
https://git.kernel.org/stable/c/7b4f8a1586c42d3af…

Impacted products

2 products

Vendor	Product	Version
Linux	Linux	Affected: d688d8585e6bea5e4e37f7497feea93b6b0a469c , < 0ae0d2b5c5a1b39c0b3c15d96b32a5b0c583d519 (git) Affected: d688d8585e6bea5e4e37f7497feea93b6b0a469c , < b413ec5b23e3445dc9c4f273116078e2d4747626 (git) Affected: d688d8585e6bea5e4e37f7497feea93b6b0a469c , < 81cf7f1413862f87b078920c838460a6a88aa030 (git) Affected: d688d8585e6bea5e4e37f7497feea93b6b0a469c , < 7b4f8a1586c42d3afc3c0ac779af2db7ab1a5c55 (git)
Linux	Linux	Affected: 6.9 Unaffected: 0 , < 6.9 (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/nfs4state.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "lessThan": "0ae0d2b5c5a1b39c0b3c15d96b32a5b0c583d519",
              "status": "affected",
              "version": "d688d8585e6bea5e4e37f7497feea93b6b0a469c",
              "versionType": "git"
            },
            {
              "lessThan": "b413ec5b23e3445dc9c4f273116078e2d4747626",
              "status": "affected",
              "version": "d688d8585e6bea5e4e37f7497feea93b6b0a469c",
              "versionType": "git"
            },
            {
              "lessThan": "81cf7f1413862f87b078920c838460a6a88aa030",
              "status": "affected",
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              "versionType": "git"
            },
            {
              "lessThan": "7b4f8a1586c42d3afc3c0ac779af2db7ab1a5c55",
              "status": "affected",
              "version": "d688d8585e6bea5e4e37f7497feea93b6b0a469c",
              "versionType": "git"
            }
          ]
        },
        {
          "defaultStatus": "affected",
          "product": "Linux",
          "programFiles": [
            "fs/nfsd/nfs4state.c"
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          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "6.9"
            },
            {
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              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
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            {
              "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": "6.12.109",
                  "versionStartIncluding": "6.9",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.18.50",
                  "versionStartIncluding": "6.9",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "7.2.4",
                  "versionStartIncluding": "6.9",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "7.3-rc1",
                  "versionStartIncluding": "6.9",
                  "vulnerable": true
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              "negate": false,
              "operator": "OR"
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      "descriptions": [
        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nNFSD: Prevent client use-after-free during NFSv4.0 revoked-state cleanup\n\nnfs40_clean_admin_revoked() takes a stateid reference under\nclp-\u003ecl_lock, drops nn-\u003eclient_lock, and calls\nnfsd4_drop_revoked_stid(), which dereferences the stateid\u0027s client\nthrough s-\u003esc_client-\u003ecl_lock.  The stateid reference does not pin the\nclient, so a teardown racing the dropped lock can free the client\nwhile nfsd4_drop_revoked_stid() is still using it.\n\nThis cleanup runs from the laundromat, so a periodic sweep can race\nforce_expire_client() driven by a write to the clients/\u003cid\u003e/ctl file.\n\nSkip a client that is already expiring and otherwise pin it with\ncl_rpc_users under client_lock before dropping the lock, matching\nnfsd4_revoke_states()."
        }
      ],
      "metrics": [
        {
          "cvssV3_1": {
            "baseScore": 9.8,
            "baseSeverity": "CRITICAL",
            "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H",
            "version": "3.1"
          },
          "scenarios": [
            {
              "lang": "en",
              "value": "AV:N - The UAF is in nfsd NFSv4.0 revoked-state cleanup (nfs40_clean_admin_revoked). A remote peer reaches it over TCP/2049 via nfsd_dispatch to nfsd4_proc_compound: SETCLIENTID/SETCLIENTID_CONFIRM (ALLOWED_WITHOUT_FH) call expire_client() while the laundromat still uses the client.\nAC:L - The attacker controls the expire side by retrying SETCLIENTID_CONFIRM around the known lease interval, or by inducing the documented clients/\u003cid\u003e/ctl expire of a misbehaving client. Cleanup drops client_lock without pinning cl_rpc_users, so mark_client_expired_locked succeeds; this is not a race outside attacker influence.\nPR:N - OP_SETCLIENTID and OP_SETCLIENTID_CONFIRM are ALLOWED_WITHOUT_FH/ALLOWED_ON_ABSENT_FS with no export check. Typical nfsd AUTH_SYS/AUTH_NULL deployments never verify RPC credentials, so any host that can reach TCP/2049 can create NFSv4.0 state and trigger the expire.\nUI:N - The attacker drives the NFS compounds that establish state and expire the client. Administrative revoke or ctl expire is a server operational condition (unexport or response to a misbehaving client), not a required victim user action.\nS:U - The freed object is struct nfs4_client in the NFS server kernel. Impact remains in that kernel security authority; there is no VM, IOMMU, or sandbox boundary crossing.\nC:H - nfsd4_drop_revoked_stid() and nfs4_put_stid() dereference s-\u003esc_client after expire_client() frees the nfs4_client. Reclaim of that slab lets an attacker groom contents and disclose kernel memory. Per kernel guidance a UAF is C:H.\nI:H - nfs4_put_stid() lock-and-idr_remove on the freed client\u0027s cl_lock/cl_stateids, concurrent with __destroy_client() list walks, is a slab UAF write primitive usable for heap corruption and control-flow hijacking. Per kernel guidance a UAF is I:H.\nA:H - Use of the freed nfs4_client spinlock, IDR, and lists oopses or panics the nfsd host, fully denying service of the NFS server."
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-09-13T06:32:40.908Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
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          "url": "https://git.kernel.org/stable/c/b413ec5b23e3445dc9c4f273116078e2d4747626"
        },
        {
          "url": "https://git.kernel.org/stable/c/81cf7f1413862f87b078920c838460a6a88aa030"
        },
        {
          "url": "https://git.kernel.org/stable/c/7b4f8a1586c42d3afc3c0ac779af2db7ab1a5c55"
        }
      ],
      "title": "NFSD: Prevent client use-after-free during NFSv4.0 revoked-state cleanup",
      "x_generator": {
        "engine": "bippy-1.2.0"
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  "cveMetadata": {
    "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
    "assignerShortName": "Linux",
    "cveId": "CVE-2026-89658",
    "datePublished": "2026-09-11T19:45:46.857Z",
    "dateReserved": "2026-09-11T19:38:34.743Z",
    "dateUpdated": "2026-09-13T06:32:40.908Z",
    "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-MR23-3FXM-CW86

CVE-2026-89658 (GCVE-0-2026-89658)

Tags

Sightings

Nomenclature