CVE-2026-43350 (GCVE-0-2026-43350)

Vulnerability from cvelistv5 – Published: 2026-05-08 13:41 – Updated: 2026-05-08 13:41
VLAI?
Title
smb: client: require a full NFS mode SID before reading mode bits
Summary
In the Linux kernel, the following vulnerability has been resolved: smb: client: require a full NFS mode SID before reading mode bits parse_dacl() treats an ACE SID matching sid_unix_NFS_mode as an NFS mode SID and reads sid.sub_auth[2] to recover the mode bits. That assumes the ACE carries three subauthorities, but compare_sids() only compares min(a, b) subauthorities. A malicious server can return an ACE with num_subauth = 2 and sub_auth[] = {88, 3}, which still matches sid_unix_NFS_mode and then drives the sub_auth[2] read four bytes past the end of the ACE. Require num_subauth >= 3 before treating the ACE as an NFS mode SID. This keeps the fix local to the special-SID mode path without changing compare_sids() semantics for the rest of cifsacl.
Severity ?
No CVSS data available.
Assigner
References
Impacted products
Vendor Product Version
Linux Linux Affected: e2f8fbfb8d09c06decde162090fac3ee220aa280 , < b53b8e98c23310294fc45fc686db5ee860311896 (git)
Affected: e2f8fbfb8d09c06decde162090fac3ee220aa280 , < c8eef12af1cc73031639ea7cf16e0b10e2536b0b (git)
Affected: e2f8fbfb8d09c06decde162090fac3ee220aa280 , < 38a69f08ee82c450d3e4168707fff2e317dc3ff7 (git)
Affected: e2f8fbfb8d09c06decde162090fac3ee220aa280 , < f8488c07bea2431ee12a6067d736578064fa46b4 (git)
Affected: e2f8fbfb8d09c06decde162090fac3ee220aa280 , < 2757ad3e4b6f9e0fed4c7739594e702abc5cab21 (git)
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    Linux Linux Affected: 5.4
Unaffected: 0 , < 5.4 (semver)
Unaffected: 6.6.136 , ≤ 6.6.* (semver)
Unaffected: 6.12.84 , ≤ 6.12.* (semver)
Unaffected: 6.18.25 , ≤ 6.18.* (semver)
Unaffected: 7.0.2 , ≤ 7.0.* (semver)
Unaffected: 7.1-rc1 , ≤ * (original_commit_for_fix)
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{
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      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "fs/smb/client/cifsacl.c"
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              "versionType": "semver"
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              "status": "unaffected",
              "version": "7.1-rc1",
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      "cpeApplicability": [
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          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nsmb: client: require a full NFS mode SID before reading mode bits\n\nparse_dacl() treats an ACE SID matching sid_unix_NFS_mode as an NFS\nmode SID and reads sid.sub_auth[2] to recover the mode bits.\n\nThat assumes the ACE carries three subauthorities, but compare_sids()\nonly compares min(a, b) subauthorities.  A malicious server can return\nan ACE with num_subauth = 2 and sub_auth[] = {88, 3}, which still\nmatches sid_unix_NFS_mode and then drives the sub_auth[2] read four\nbytes past the end of the ACE.\n\nRequire num_subauth \u003e= 3 before treating the ACE as an NFS mode SID.\nThis keeps the fix local to the special-SID mode path without changing\ncompare_sids() semantics for the rest of cifsacl."
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-05-08T13:41:53.276Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
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        {
          "url": "https://git.kernel.org/stable/c/f8488c07bea2431ee12a6067d736578064fa46b4"
        },
        {
          "url": "https://git.kernel.org/stable/c/2757ad3e4b6f9e0fed4c7739594e702abc5cab21"
        }
      ],
      "title": "smb: client: require a full NFS mode SID before reading mode bits",
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    "assignerShortName": "Linux",
    "cveId": "CVE-2026-43350",
    "datePublished": "2026-05-08T13:41:53.276Z",
    "dateReserved": "2026-05-01T14:12:56.003Z",
    "dateUpdated": "2026-05-08T13:41:53.276Z",
    "state": "PUBLISHED"
  },
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      "date": "2026-05-09",
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  }
}


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