CVE-2026-64138 (GCVE-0-2026-64138)

Vulnerability from cvelistv5 – Published: 2026-07-19 15:40 – Updated: 2026-07-20 13:43
VLAI
Title
ksmbd: validate SID in parent security descriptor during ACL inheritance
Summary
In the Linux kernel, the following vulnerability has been resolved: ksmbd: validate SID in parent security descriptor during ACL inheritance Introduce smb_validate_ntsd_sid() helper to safely validate Owner SID and Group SID inside the NT Security Descriptor (smb_ntsd) retrieved from the parent directory.
Severity
8.8 (High)
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Assigner
References
Impacted products
Vendor Product Version
Linux Linux Affected: e2f34481b24db2fd634b5edb0a5bd0e4d38cc6e9 , < f0e5c9c663badc9982e6941322eef1cb17de0f11 (git)
Affected: e2f34481b24db2fd634b5edb0a5bd0e4d38cc6e9 , < 18d8db24b0a5b7be4829238dd4022236df02d421 (git)
Affected: e2f34481b24db2fd634b5edb0a5bd0e4d38cc6e9 , < 1c9d0646a9959752f11ca1080dc1ff26bd1756cb (git)
Affected: e2f34481b24db2fd634b5edb0a5bd0e4d38cc6e9 , < 69f030cf95488ae1186c72ac8c66fd279664ea7f (git)
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Linux Linux Affected: 5.15
Unaffected: 0 , < 5.15 (semver)
Unaffected: 6.12.92 , ≤ 6.12.* (semver)
Unaffected: 6.18.34 , ≤ 6.18.* (semver)
Unaffected: 7.0.11 , ≤ 7.0.* (semver)
Unaffected: 7.1 , ≤ * (original_commit_for_fix)
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{
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          "product": "Linux",
          "programFiles": [
            "fs/smb/server/smbacl.c"
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              "operator": "OR"
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          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nksmbd: validate SID in parent security descriptor during ACL inheritance\n\nIntroduce smb_validate_ntsd_sid() helper to safely validate Owner SID\nand Group SID inside the NT Security Descriptor (smb_ntsd) retrieved\nfrom the parent directory."
        }
      ],
      "metrics": [
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          "cvssV3_1": {
            "baseScore": 8.8,
            "baseSeverity": "HIGH",
            "vectorString": "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
            "version": "3.1"
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      "providerMetadata": {
        "dateUpdated": "2026-07-20T13:43:43.352Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
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        },
        {
          "url": "https://git.kernel.org/stable/c/69f030cf95488ae1186c72ac8c66fd279664ea7f"
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      "title": "ksmbd: validate SID in parent security descriptor during ACL inheritance",
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    "assignerShortName": "Linux",
    "cveId": "CVE-2026-64138",
    "datePublished": "2026-07-19T15:40:31.760Z",
    "dateReserved": "2026-07-19T07:54:57.037Z",
    "dateUpdated": "2026-07-20T13:43:43.352Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2",
  "vulnerability-lookup:meta": {
    "epss": {
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      "date": "2026-07-21",
      "epss": "0.00414",
      "percentile": "0.33712"
    },
    "microsoft_vex": {
      "current_release_date": "2026-07-21T01:02:00.000Z",
      "cve": "CVE-2026-64138",
      "id": "msrc_CVE-2026-64138",
      "initial_release_date": "2026-07-21T01:02:00.000Z",
      "product_status:known_affected": "1",
      "source": "Microsoft CSAF VEX",
      "status": "final",
      "title": "ksmbd: validate SID in parent security descriptor during ACL inheritance",
      "url": "https://msrc.microsoft.com/csaf/vex/2026/msrc_cve-2026-64138.json",
      "version": "1"
    },
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    "redhat_vex": {
      "aggregate_severity": "None",
      "current_release_date": "2026-07-21T07:52:28+00:00",
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      "product_status:known_not_affected": "275",
      "source": "Red Hat CSAF VEX",
      "status": "final",
      "title": "kernel: ksmbd: validate SID in parent security descriptor during ACL inheritance",
      "url": "https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-64138.json",
      "version": "3"
    }
  }
}



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Forecast uses a logistic model when the trend is rising, or an exponential decay model when the trend is falling. Fitted via linearized least squares.

Sightings

Author Source Type Date Other

Nomenclature

  • Seen: The vulnerability was mentioned, discussed, or observed by the user.
  • Confirmed: The vulnerability has been validated from an analyst's perspective.
  • Published Proof of Concept: A public proof of concept is available for this vulnerability.
  • Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
  • Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
  • Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
  • Not confirmed: The user expressed doubt about the validity of the vulnerability.
  • Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.


Detection rules are retrieved from Rulezet.