CVE-2026-53244 (GCVE-0-2026-53244)
Vulnerability from cvelistv5
Published
2026-06-25 08:39
Modified
2026-08-05 12:34
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: VFS: fix possible failure to unlock in nfsd4_create_file() atomic_create() in fs/namei.c drops the reference to the dentry when it returns an error. This behaviour was imported into dentry_create() so that it will drop the reference if an error is returned from atomic_create(), though not if vfs_create() returns an error (in the case where ->atomic_create is not supported). The caller - nfsd4_create_file() - is made aware of this by checking path->dentry, which will either be a counted reference to a dentry, or an error pointer. However the change to use start_creating()/end_creating() (which landed shortly before the dentry_create() change landed, though was likely developed around the same time) means that nfsd4_create_file() *needs* a valid dentry so that it can unlock the parent. The net result is that if NFSD exports a filesystem which uses ->atomic_create, and if a call to ->atomic_create returns an error, then nfsd4_create_file() will pass an error pointer to end_creating() and the parent will not be unlocked. Fix this by changing dentry_create() to make sure path->dentry is always a valid dentry, never an error-pointer. The actual error is already returned a different way. Note that if ->atomic_create() returns a different dentry (which may not be possible in practice) we are guaranteed (because it is only ever provided by d_spliace_alias()) that it will have the same d_parent and so it will have the same effect when passed to end_creating().
References
Impacted products
Vendor Product Version
Linux Linux Version: 64a989dbd144e0622371396461b11335459692d2
Version: 64a989dbd144e0622371396461b11335459692d2
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{
  "containers": {
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "fs/namei.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "lessThan": "ee1f40759a50b1800c98c1c369afd5b3e44ad987",
              "status": "affected",
              "version": "64a989dbd144e0622371396461b11335459692d2",
              "versionType": "git"
            },
            {
              "lessThan": "e824bbd4d224cce4b5fb59cc9dcd3447fe0b7e44",
              "status": "affected",
              "version": "64a989dbd144e0622371396461b11335459692d2",
              "versionType": "git"
            }
          ]
        },
        {
          "defaultStatus": "affected",
          "product": "Linux",
          "programFiles": [
            "fs/namei.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "7.0"
            },
            {
              "lessThan": "7.0",
              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "7.0.*",
              "status": "unaffected",
              "version": "7.0.13",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "7.1",
              "versionType": "original_commit_for_fix"
            }
          ]
        }
      ],
      "cpeApplicability": [
        {
          "nodes": [
            {
              "cpeMatch": [
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "7.0.13",
                  "versionStartIncluding": "7.0",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "7.1",
                  "versionStartIncluding": "7.0",
                  "vulnerable": true
                }
              ],
              "negate": false,
              "operator": "OR"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nVFS: fix possible failure to unlock in nfsd4_create_file()\n\natomic_create() in fs/namei.c drops the reference to the dentry\nwhen it returns an error.\nThis behaviour was imported into dentry_create() so that it\nwill drop the reference if an error is returned from atomic_create(),\nthough not if vfs_create() returns an error (in the case where\n-\u003eatomic_create is not supported).\n\nThe caller - nfsd4_create_file() - is made aware of this by checking\npath-\u003edentry, which will either be a counted reference to a dentry, or\nan error pointer.\n\nHowever the change to use start_creating()/end_creating() (which landed\nshortly before the dentry_create() change landed, though was likely\ndeveloped around the same time) means that nfsd4_create_file() *needs* a\nvalid dentry so that it can unlock the parent.\n\nThe net result is that if NFSD exports a filesystem which uses\n-\u003eatomic_create, and if a call to -\u003eatomic_create returns an error, then\nnfsd4_create_file() will pass an error pointer to end_creating()\nand the parent will not be unlocked.\n\nFix this by changing dentry_create() to make sure path-\u003edentry is always\na valid dentry, never an error-pointer.  The actual error is already\nreturned a different way.\n\nNote that if -\u003eatomic_create() returns a different dentry (which may not\nbe possible in practice) we are guaranteed (because it is only ever\nprovided by d_spliace_alias()) that it will have the same d_parent and\nso it will have the same effect when passed to end_creating()."
        }
      ],
      "metrics": [
        {
          "cvssV3_1": {
            "baseScore": 7.5,
            "baseSeverity": "HIGH",
            "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H",
            "version": "3.1"
          },
          "scenarios": [
            {
              "lang": "en",
              "value": "AV:N - The vulnerable path is reachable through NFSv4 network COMPOUND/OPEN create requests handled by in-kernel nfsd.\nAC:L - An attacker can directly send an OPEN create request to an affected export, and on atomic_open filesystems can choose inputs or conditions that make atomic_open return an error. No race or hard-to-control timing is required.\nPR:N - In the highest reasonable deployment, a writable NFS export using AUTH_SYS/AUTH_NULL or host-based access lets a remote client reach this path without prior authenticated privileges. The attacker only needs network access to an export that permits creates.\nUI:N - No victim action is required after the NFS service and export are available; the attacker sends the NFS request directly.\nS:U - The impact is within the same kernel/NFS server security authority and does not cross a VM, IOMMU, or sandbox boundary.\nC:N - The bug leaves a directory lock held but does not expose kernel or file data and is not a memory corruption primitive.\nI:N - The flaw does not provide unauthorized modification of data or control flow; it causes failed cleanup after an atomic_open error.\nA:H - Failure to unlock the parent directory i_rwsem can hang subsequent operations on that directory and can tie up nfsd service threads, producing a high-impact denial of service."
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-08-05T12:34:29.358Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "references": [
        {
          "url": "https://git.kernel.org/stable/c/ee1f40759a50b1800c98c1c369afd5b3e44ad987"
        },
        {
          "url": "https://git.kernel.org/stable/c/e824bbd4d224cce4b5fb59cc9dcd3447fe0b7e44"
        }
      ],
      "title": "VFS: fix possible failure to unlock in nfsd4_create_file()",
      "x_generator": {
        "engine": "bippy-1.2.0"
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
    "assignerShortName": "Linux",
    "cveId": "CVE-2026-53244",
    "datePublished": "2026-06-25T08:39:38.468Z",
    "dateReserved": "2026-06-09T07:44:35.393Z",
    "dateUpdated": "2026-08-05T12:34:29.358Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}


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