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nfsd: Reset write verifier when async COPY writeback fails

Type: advisorySource: Official CVE List1 source record

In the Linux kernel, the following vulnerability has been resolved: nfsd: Reset write verifier when async COPY writeback fails Async COPY captures nn->writeverf at request time and reports it to the client via CB_OFFLOAD after the worker kthread completes. When the post-copy vfs_fsync_range() or filemap_check_wb_err() in _nfsd_copy_file_range() reports an error, the worker correctly leaves NFSD4_COPY_F_COMMITTED clear so that CB_OFFLOAD encodes wr_stable_how as NFS_UNSTABLE, but the server's write verifier is not rotated. A client that receives NFS_UNSTABLE in CB_OFFLOAD follows up with COMMIT to make the copied data durable. With the verifier unchanged, COMMIT returns the same value the client just received via CB_OFFLOAD, and the client concludes the copy is durable -- silently dropping the data whose writeback in fact failed. This violates the UNSTABLE+COMMIT durability contract (RFC 7862 section 15.1, RFC 8881 section 18.32) and matches the bug just fixed in nfsd_vfs_write() and nfsd_commit(). Rotate nn->writeverf at the writeback-failure site. The async COPY worker has no svc_rqst, so commit_reset_write_verifier() is not available here; calling nfsd_reset_write_verifier() directly mirrors the trace-less reset already used by nfsd_file_check_write_error() for the same purpose. Filter out -EAGAIN and -ESTALE, matching commit_reset_write_verifier(), since neither indicates a durable-storage failure.

Announced Source revision 1
Original source ↗

CVE-2026-89706

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-2026-89706

Linux

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

Affected versions
Not stated in this record
Fixed versions
Not stated in this record
Prerequisites
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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": "817c6eb975798647c4bbbfc9eb288aa413ec7f65",
        "lessThan": "cc5f7cef0659a27c13dd33edd8e2f79257b095c6",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "eac0b17a77fbd763d305a5eaa4fd1119e5a0fe0d",
        "lessThan": "c6d2f6372c7e0f76b9c148ff7696aec64da0b5b7",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "eac0b17a77fbd763d305a5eaa4fd1119e5a0fe0d",
        "lessThan": "8a08ffe73eb2aa6bc6f88763da7e2b55bab6493a",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "eac0b17a77fbd763d305a5eaa4fd1119e5a0fe0d",
        "lessThan": "6b13d26cc21b6320a3c61d5e4cee2ce9a589b181",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "eac0b17a77fbd763d305a5eaa4fd1119e5a0fe0d",
        "lessThan": "31d4d0a62ec4bafbcdbad142f11ab1f90794b1d0",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "eac0b17a77fbd763d305a5eaa4fd1119e5a0fe0d",
        "lessThan": "591134e059e3456180244a826d6917cdc183140b",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "eac0b17a77fbd763d305a5eaa4fd1119e5a0fe0d",
        "lessThan": "bf0cd31a9abcb728c17d79b4c2cc533612a8b6af",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "eac0b17a77fbd763d305a5eaa4fd1119e5a0fe0d",
        "lessThan": "f5cb2276954cb80987a93ef9f9dfbfdbfc0f10b9",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "5.10.220",
        "lessThan": "5.10.270",
        "versionType": "semver"
      }
    ],
    "programFiles": [
      "fs/nfsd/nfs4proc.c"
    ],
    "defaultStatus": "unaffected"
  },
  {
    "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
    "vendor": "Linux",
    "product": "Linux",
    "versions": [
      {
        "status": "affected",
        "version": "5.14"
      },
      {
        "status": "unaffected",
        "version": "0",
        "lessThan": "5.14",
        "versionType": "semver"
      },
      {
        "status": "unaffected",
        "version": "5.10.270",
        "versionType": "semver",
        "lessThanOrEqual": "5.10.*"
      },
      {
        "status": "unaffected",
        "version": "5.15.221",
        "versionType": "semver",
        "lessThanOrEqual": "5.15.*"
      },
      {
        "status": "unaffected",
        "version": "6.1.188",
        "versionType": "semver",
        "lessThanOrEqual": "6.1.*"
      },
      {
        "status": "unaffected",
        "version": "6.6.157",
        "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/nfs4proc.c"
    ],
    "defaultStatus": "affected"
  }
]
Related CVEs
CVE-2026-89706

Source reference: /cveMetadata/cveId

Publisher severity

high

Source reference: /containers/cna/metrics

Event
#35189 · Revision 1
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Publisher date
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