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FKIE_CVE-2026-89707

Vulnerability from fkie_nvd - Published: 2026-09-11 20:19 - Updated: 2026-09-14 13:19
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: nfsd: release path refs on follow_down() error nfsd_cross_mnt() initializes a local struct path with mntget() and dget() before calling follow_down(). On a negative return the error arm jumps to out without releasing those references: err = follow_down(&path, follow_flags); if (err < 0) goto out; follow_down() never drops the caller's entry-time refs on any error sub-case; for example a pre-cross d_manage() failure leaves path untouched, so the mntget()/dget() taken on entry survive the call. Every other early-exit arm in nfsd_cross_mnt() (other-namespace return, IS_ERR(exp2), and the success tail after the swap) already calls path_put(&path); the err < 0 arm is the lone omission. The leak inflates mnt_count and d_count on each failed cross-mount, blocking umount and pinning dentries against the shrinker, and is reachable by any authenticated NFS client through nfsd_lookup_dentry or the NFSv4 READDIR encode path. Fix by calling path_put(&path) before the goto out in the err < 0 arm so the entry-time refs are released on all follow_down() error returns.
References
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/085cfde7c2186acaad103f02d2c25435ad5224e9
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/194316df81263519156ebe714c4a286bee00e5be
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/2bc4343308d85ee4e0dd3877b384306c96f114c2
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/467d56fd3ff57447a790c6dc3ede2d02a947d224
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/6cba08dc1922140d260cfeb30bbda4ee1bf869d8
Impacted products
Vendor Product Version
To clipboard 

{
  "affected": [
    {
      "affectedData": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "fs/nfsd/vfs.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "lessThan": "085cfde7c2186acaad103f02d2c25435ad5224e9",
              "status": "affected",
              "version": "cc53ce53c86924bfe98a12ea20b7465038a08792",
              "versionType": "git"
            },
            {
              "lessThan": "194316df81263519156ebe714c4a286bee00e5be",
              "status": "affected",
              "version": "cc53ce53c86924bfe98a12ea20b7465038a08792",
              "versionType": "git"
            },
            {
              "lessThan": "467d56fd3ff57447a790c6dc3ede2d02a947d224",
              "status": "affected",
              "version": "cc53ce53c86924bfe98a12ea20b7465038a08792",
              "versionType": "git"
            },
            {
              "lessThan": "2bc4343308d85ee4e0dd3877b384306c96f114c2",
              "status": "affected",
              "version": "cc53ce53c86924bfe98a12ea20b7465038a08792",
              "versionType": "git"
            },
            {
              "lessThan": "6cba08dc1922140d260cfeb30bbda4ee1bf869d8",
              "status": "affected",
              "version": "cc53ce53c86924bfe98a12ea20b7465038a08792",
              "versionType": "git"
            }
          ]
        },
        {
          "defaultStatus": "affected",
          "product": "Linux",
          "programFiles": [
            "fs/nfsd/vfs.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "2.6.38"
            },
            {
              "lessThan": "2.6.38",
              "status": "unaffected",
              "version": "0",
              "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"
            }
          ]
        }
      ],
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    }
  ],
  "cveTags": [],
  "descriptions": [
    {
      "lang": "en",
      "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nnfsd: release path refs on follow_down() error\n\nnfsd_cross_mnt() initializes a local struct path with mntget() and\ndget() before calling follow_down(). On a negative return the error\narm jumps to out without releasing those references:\n\n    err = follow_down(\u0026path, follow_flags);\n    if (err \u003c 0)\n            goto out;\n\nfollow_down() never drops the caller\u0027s entry-time refs on any error\nsub-case; for example a pre-cross d_manage() failure leaves path\nuntouched, so the mntget()/dget() taken on entry survive the call.\n\nEvery other early-exit arm in nfsd_cross_mnt() (other-namespace\nreturn, IS_ERR(exp2), and the success tail after the swap) already\ncalls path_put(\u0026path); the err \u003c 0 arm is the lone omission. The\nleak inflates mnt_count and d_count on each failed cross-mount,\nblocking umount and pinning dentries against the shrinker, and is\nreachable by any authenticated NFS client through nfsd_lookup_dentry\nor the NFSv4 READDIR encode path.\n\nFix by calling path_put(\u0026path) before the goto out in the err \u003c 0\narm so the entry-time refs are released on all follow_down() error\nreturns."
    }
  ],
  "id": "CVE-2026-89707",
  "lastModified": "2026-09-14T13:19:20.690",
  "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": "2026-09-11T20:19:58.017",
  "references": [
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/085cfde7c2186acaad103f02d2c25435ad5224e9"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/194316df81263519156ebe714c4a286bee00e5be"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/2bc4343308d85ee4e0dd3877b384306c96f114c2"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/467d56fd3ff57447a790c6dc3ede2d02a947d224"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/6cba08dc1922140d260cfeb30bbda4ee1bf869d8"
    }
  ],
  "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
  "vulnStatus": "Received"
}



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