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Critical

NFSD: check truncate permission under inode lock

Type: advisorySource: Official CVE List1 source record

In the Linux kernel, the following vulnerability has been resolved: NFSD: check truncate permission under inode lock nfsd_setattr() checks whether a size update needs NFSD_MAY_TRUNC before it takes inode_lock(). The comparison uses the file size sampled by that unlocked read, but the actual ATTR_SIZE update is applied later under inode_lock() by notify_change(). This leaves a TOCTOU window for append-only files. If a client sends a SETATTR that does not shrink the file at the time of the unlocked sample, a concurrent append can extend the file before nfsd_setattr() takes inode_lock(). notify_change() then applies a real truncation without the NFSD_MAY_TRUNC check that rejects IS_APPEND(inode). The VFS truncate syscall paths perform their own append-only checks before calling notify_change(), so NFSD must make this decision against the locked size it is about to change. Split the write-count acquisition from the truncation permission check. Keep get_write_access() before the locked setattr work, then recheck whether the requested size is below i_size_read(inode) after inode_lock() has been acquired and before notify_change(ATTR_SIZE). This also avoids the plain unlocked inode->i_size load.

Announced Source revision 1
Original source ↗

CVE-2026-89713

Primary source · Revision 1

Imported from structured advisory data. Source references identify upstream records or fields; verify affected versions and your deployed configuration.

Security context

Source reference: cve:CVE-2026-89713

Linux

Source reference: /containers/cna/affected/0/product

Affected versions
Not stated in this record
Fixed versions
Not stated in this record
Prerequisites
Not stated in this record

Linux

Source reference: /containers/cna/affected/1/product

Affected versions
Not stated in this record
Fixed versions
Not stated in this record
Prerequisites
Not stated in this record

Structured affected-version data

Original package identities and version rules from this source.

[
  {
    "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
    "vendor": "Linux",
    "product": "Linux",
    "versions": [
      {
        "status": "affected",
        "version": "783112f7401ff449d979530209b3f6c2594fdb4e",
        "lessThan": "52d0c5bdfe232c9974d4b11f97078b9c7814f05d",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "783112f7401ff449d979530209b3f6c2594fdb4e",
        "lessThan": "3afa17d93ba8c925f49370c816c6dae5112d8c24",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "783112f7401ff449d979530209b3f6c2594fdb4e",
        "lessThan": "d8352da196349182e1afd5a93308256cddc0a97d",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "783112f7401ff449d979530209b3f6c2594fdb4e",
        "lessThan": "44086254479035de42ca3d286ecf25521d4e6325",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "783112f7401ff449d979530209b3f6c2594fdb4e",
        "lessThan": "b778e0e0a16759f22a70579c3cf8d254a40d4a7f",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "604a3c407026d6162d15300478e63f901e435efc",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "cc4d5dc73841b98d33cdfb9822d70b0aac4beca5",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "3ee4f442e5b37a537297b812557b1163f96b5399",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "a3c6cbc4eac4473ed5461d5faae2794d3e5c0e44",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "982898d7f97a35447403c3fcecc0d96c646ce101",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "3.2.89",
        "lessThan": "3.3",
        "versionType": "semver"
      },
      {
        "status": "affected",
        "version": "3.16.44",
        "lessThan": "3.17",
        "versionType": "semver"
      },
      {
        "status": "affected",
        "version": "4.4.53",
        "lessThan": "4.5",
        "versionType": "semver"
      },
      {
        "status": "affected",
        "version": "4.9.14",
        "lessThan": "4.10",
        "versionType": "semver"
      },
      {
        "status": "affected",
        "version": "4.10.2",
        "lessThan": "4.11",
        "versionType": "semver"
      }
    ],
    "programFiles": [
      "fs/nfsd/vfs.c"
    ],
    "defaultStatus": "unaffected"
  },
  {
    "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
    "vendor": "Linux",
    "product": "Linux",
    "versions": [
      {
        "status": "affected",
        "version": "4.11"
      },
      {
        "status": "unaffected",
        "version": "0",
        "lessThan": "4.11",
        "versionType": "semver"
      },
      {
        "status": "unaffected",
        "version": "6.6.160",
        "versionType": "semver",
        "lessThanOrEqual": "6.6.*"
      },
      {
        "status": "unaffected",
        "version": "6.12.109",
        "versionType": "semver",
        "lessThanOrEqual": "6.12.*"
      },
      {
        "status": "unaffected",
        "version": "6.18.50",
        "versionType": "semver",
        "lessThanOrEqual": "6.18.*"
      },
      {
        "status": "unaffected",
        "version": "7.2.4",
        "versionType": "semver",
        "lessThanOrEqual": "7.2.*"
      },
      {
        "status": "unaffected",
        "version": "7.3",
        "versionType": "original_commit_for_fix",
        "lessThanOrEqual": "*"
      }
    ],
    "programFiles": [
      "fs/nfsd/vfs.c"
    ],
    "defaultStatus": "affected"
  }
]
Related CVEs
CVE-2026-89713

Source reference: /cveMetadata/cveId

Publisher severity

critical

Source reference: /containers/cna/metrics

Event
#46712 · Revision 1
Added to Heist Feed
Publisher date
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