FKIE_CVE-2026-89660

Vulnerability from fkie_nvd - Published: 2026-09-11 20:19 - Updated: 2026-10-19 09:18
Severity
9.8 (Critical) - CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Summary
In the Linux kernel, the following vulnerability has been resolved: NFSD: Prevent client use-after-free during admin state revocation A stateid holds only a bare pointer to its nfs4_client; a stateid reference does not pin it. The client survives only because __destroy_client() drains its stateids before free_client() runs. nfsd4_revoke_states() drops nn->client_lock across revoke_one_stid(), which dereferences the client to revoke a stateid and read clp->cl_minorversion. A teardown racing the dropped lock can free the client first. Pinning cl_rpc_users under client_lock blocks the DESTROY_CLIENTID and EXCHANGE_ID teardown, which refuses while cl_rpc_users is non-zero. force_expire_client() ignores it: once its wait for cl_rpc_users to reach zero has passed, a later pin goes unnoticed. Under client_lock, skip a client whose cl_time is already zero -- force_expire_client() clears it there before waiting -- otherwise pin cl_rpc_users before dropping the lock. The walk then either sees the expiry and skips, or pins in time for that wait to cover the revoke.
References
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/549bd9868e9d77b07ea94870940d64342829c6ad
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/bf1f948691523282cc4905bc6cd325e0c0b49e6a
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/e1ba4d3c5bfdca3f013b8cbc829ae2f7975d8608
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/e270e5a0778e5bff852c8862ce9576ce70359393
Impacted products
Vendor Product Version
To clipboard 

{
  "affected": [
    {
      "affectedData": [
        {
          "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": "e1ba4d3c5bfdca3f013b8cbc829ae2f7975d8608",
              "status": "affected",
              "version": "1c13bf9f2e3cd5a59ef988c6c5a49fe0f02bcdfc",
              "versionType": "git"
            },
            {
              "lessThan": "549bd9868e9d77b07ea94870940d64342829c6ad",
              "status": "affected",
              "version": "1c13bf9f2e3cd5a59ef988c6c5a49fe0f02bcdfc",
              "versionType": "git"
            },
            {
              "lessThan": "bf1f948691523282cc4905bc6cd325e0c0b49e6a",
              "status": "affected",
              "version": "1c13bf9f2e3cd5a59ef988c6c5a49fe0f02bcdfc",
              "versionType": "git"
            },
            {
              "lessThan": "e270e5a0778e5bff852c8862ce9576ce70359393",
              "status": "affected",
              "version": "1c13bf9f2e3cd5a59ef988c6c5a49fe0f02bcdfc",
              "versionType": "git"
            }
          ]
        },
        {
          "defaultStatus": "affected",
          "product": "Linux",
          "programFiles": [
            "fs/nfsd/nfs4state.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "6.9"
            },
            {
              "lessThan": "6.9",
              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.12.*",
              "status": "unaffected",
              "version": "6.12.111",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.18.*",
              "status": "unaffected",
              "version": "6.18.51",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "7.2.*",
              "status": "unaffected",
              "version": "7.2.4",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "7.3",
              "versionType": "original_commit_for_fix"
            }
          ]
        }
      ],
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    }
  ],
  "cveTags": [],
  "descriptions": [
    {
      "lang": "en",
      "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nNFSD: Prevent client use-after-free during admin state revocation\n\nA stateid holds only a bare pointer to its nfs4_client; a stateid\nreference does not pin it.  The client survives only because\n__destroy_client() drains its stateids before free_client() runs.\n\nnfsd4_revoke_states() drops nn-\u003eclient_lock across revoke_one_stid(),\nwhich dereferences the client to revoke a stateid and read\nclp-\u003ecl_minorversion.  A teardown racing the dropped lock can free\nthe client first.\n\nPinning cl_rpc_users under client_lock blocks the DESTROY_CLIENTID and\nEXCHANGE_ID teardown, which refuses while cl_rpc_users is non-zero.\nforce_expire_client() ignores it: once its wait for cl_rpc_users to\nreach zero has passed, a later pin goes unnoticed.\n\nUnder client_lock, skip a client whose cl_time is already zero --\nforce_expire_client() clears it there before waiting -- otherwise pin\ncl_rpc_users before dropping the lock.  The walk then either sees the\nexpiry and skips, or pins in time for that wait to cover the revoke."
    }
  ],
  "id": "CVE-2026-89660",
  "lastModified": "2026-10-19T09:18:03.880",
  "metrics": {
    "cvssMetricV31": [
      {
        "cvssData": {
          "attackComplexity": "LOW",
          "attackVector": "NETWORK",
          "availabilityImpact": "HIGH",
          "baseScore": 9.8,
          "baseSeverity": "CRITICAL",
          "confidentialityImpact": "HIGH",
          "integrityImpact": "HIGH",
          "privilegesRequired": "NONE",
          "scope": "UNCHANGED",
          "userInteraction": "NONE",
          "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H",
          "version": "3.1"
        },
        "exploitabilityScore": 3.9,
        "impactScore": 5.9,
        "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "type": "Secondary"
      }
    ]
  },
  "published": "2026-09-11T20:19:52.300",
  "references": [
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/549bd9868e9d77b07ea94870940d64342829c6ad"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/bf1f948691523282cc4905bc6cd325e0c0b49e6a"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/e1ba4d3c5bfdca3f013b8cbc829ae2f7975d8608"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/e270e5a0778e5bff852c8862ce9576ce70359393"
    }
  ],
  "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
  "vulnStatus": "Received"
}



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