FKIE_CVE-2026-90234

Vulnerability from fkie_nvd - Published: 2026-09-17 17:17 - Updated: 2026-10-30 13:20
Severity
7.5 (High) - CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Summary
In the Linux kernel, the following vulnerability has been resolved: NFS: Return a delegation the client fails to record When an NFS server grants a delegation in an OPEN reply, nfs_inode_set_delegation() records it on the client. However, three of its error flows return without sending DELEGRETURN. A delegation can be relinquished only by DELEGRETURN (RFC 8881 Section 20.2.4), so dropping one silently leaves the server believing the client still holds it. If the server happens to recall that delegation, the client answers CB_RECALL with NFS4ERR_BADHANDLE because it has no record of the stateid. The server revokes the delegation and moves it onto its cl_revoked list, because the client never sends the FREE_STATEID that would drain it. Every subsequent SEQUENCE reply then carries SEQ4_STATUS_RECALLABLE_STATE_REVOKED, and the client's state manager loops issuing TEST_STATEID across its delegations without ever clearing the condition. The window is easy to reach now that a server offers a write delegation on any write OPEN: a delegation recalled for one opener races a re-open that the server answers with a fresh write delegation. Instead of dropping it, hand the delegation back during these error flows.
References
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/220af23d863995091f0edeb1e6aa0945b3db8b37
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/61b23f482b2082e77d2f78bd1624f93a12ec35ce
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/6822ba1ae9b6df6a094f7f8998f1da734c85fa19
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/92533e49fe3c455088657b862cf3562260c0ce25
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/9e71e332fa2c7a48f3d00001f856a13cc2d69639
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/fe3b1c8966a27b70599d28ce7e80819adac1ff22
Impacted products
Vendor Product Version
To clipboard 

{
  "affected": [
    {
      "affectedData": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "fs/nfs/delegation.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "lessThan": "61b23f482b2082e77d2f78bd1624f93a12ec35ce",
              "status": "affected",
              "version": "ade04647dd56881e285983af3db702d56ee97e86",
              "versionType": "git"
            },
            {
              "lessThan": "9e71e332fa2c7a48f3d00001f856a13cc2d69639",
              "status": "affected",
              "version": "ade04647dd56881e285983af3db702d56ee97e86",
              "versionType": "git"
            },
            {
              "lessThan": "fe3b1c8966a27b70599d28ce7e80819adac1ff22",
              "status": "affected",
              "version": "ade04647dd56881e285983af3db702d56ee97e86",
              "versionType": "git"
            },
            {
              "lessThan": "6822ba1ae9b6df6a094f7f8998f1da734c85fa19",
              "status": "affected",
              "version": "ade04647dd56881e285983af3db702d56ee97e86",
              "versionType": "git"
            },
            {
              "lessThan": "92533e49fe3c455088657b862cf3562260c0ce25",
              "status": "affected",
              "version": "ade04647dd56881e285983af3db702d56ee97e86",
              "versionType": "git"
            },
            {
              "lessThan": "220af23d863995091f0edeb1e6aa0945b3db8b37",
              "status": "affected",
              "version": "ade04647dd56881e285983af3db702d56ee97e86",
              "versionType": "git"
            }
          ]
        },
        {
          "defaultStatus": "affected",
          "product": "Linux",
          "programFiles": [
            "fs/nfs/delegation.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "4.0"
            },
            {
              "lessThan": "4.0",
              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.1.*",
              "status": "unaffected",
              "version": "6.1.191",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.6.*",
              "status": "unaffected",
              "version": "6.6.160",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.12.*",
              "status": "unaffected",
              "version": "6.12.114",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.18.*",
              "status": "unaffected",
              "version": "6.18.57",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "7.2.*",
              "status": "unaffected",
              "version": "7.2.6",
              "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\nNFS: Return a delegation the client fails to record\n\nWhen an NFS server grants a delegation in an OPEN reply,\nnfs_inode_set_delegation() records it on the client. However, three\nof its error flows return without sending DELEGRETURN.\n\nA delegation can be relinquished only by DELEGRETURN (RFC 8881\nSection 20.2.4), so dropping one silently leaves the server believing\nthe client still holds it. If the server happens to recall that\ndelegation, the client answers CB_RECALL with NFS4ERR_BADHANDLE\nbecause it has no record of the stateid. The server revokes the\ndelegation and moves it onto its cl_revoked list, because the client\nnever sends the FREE_STATEID that would drain it. Every subsequent\nSEQUENCE reply then carries SEQ4_STATUS_RECALLABLE_STATE_REVOKED,\nand the client\u0027s state manager loops issuing TEST_STATEID across its\ndelegations without ever clearing the condition.\n\nThe window is easy to reach now that a server offers a write\ndelegation on any write OPEN: a delegation recalled for one opener\nraces a re-open that the server answers with a fresh write\ndelegation.\n\nInstead of dropping it, hand the delegation back during these error\nflows."
    }
  ],
  "id": "CVE-2026-90234",
  "lastModified": "2026-10-30T13:20:47.297",
  "metrics": {
    "cvssMetricV31": [
      {
        "cvssData": {
          "attackComplexity": "LOW",
          "attackVector": "NETWORK",
          "availabilityImpact": "HIGH",
          "baseScore": 7.5,
          "baseSeverity": "HIGH",
          "confidentialityImpact": "NONE",
          "integrityImpact": "NONE",
          "privilegesRequired": "NONE",
          "scope": "UNCHANGED",
          "userInteraction": "NONE",
          "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H",
          "version": "3.1"
        },
        "exploitabilityScore": 3.9,
        "impactScore": 3.6,
        "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "type": "Secondary"
      }
    ]
  },
  "published": "2026-09-17T17:17:19.293",
  "references": [
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/220af23d863995091f0edeb1e6aa0945b3db8b37"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/61b23f482b2082e77d2f78bd1624f93a12ec35ce"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/6822ba1ae9b6df6a094f7f8998f1da734c85fa19"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/92533e49fe3c455088657b862cf3562260c0ce25"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/9e71e332fa2c7a48f3d00001f856a13cc2d69639"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/fe3b1c8966a27b70599d28ce7e80819adac1ff22"
    }
  ],
  "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
  "vulnStatus": "Received"
}



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