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GHSA-XVVM-359F-6VGC

Vulnerability from github – Published: 2026-05-08 15:31 – Updated: 2026-05-11 09:30

Details

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 ?

7.6 (High)


                  
                    CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:L/A:H

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{
  "affected": [],
  "aliases": [
    "CVE-2026-43350"
  ],
  "database_specific": {
    "cwe_ids": [],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2026-05-08T14:16:45Z",
    "severity": "HIGH"
  },
  "details": "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.",
  "id": "GHSA-xvvm-359f-6vgc",
  "modified": "2026-05-11T09:30:30Z",
  "published": "2026-05-08T15:31:24Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-43350"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/2757ad3e4b6f9e0fed4c7739594e702abc5cab21"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/38a69f08ee82c450d3e4168707fff2e317dc3ff7"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/b53b8e98c23310294fc45fc686db5ee860311896"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/c8eef12af1cc73031639ea7cf16e0b10e2536b0b"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/f8488c07bea2431ee12a6067d736578064fa46b4"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:L/A:H",
      "type": "CVSS_V3"
    }
  ]
}

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

Vulnerability from cvelistv5 – Published: 2026-05-08 13:41 – Updated: 2026-05-11 22:22

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 ?

7.6 (High)


                        
                          CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:L/A:H

Assigner

Linux

References

5 references

URL	Tags
https://git.kernel.org/stable/c/b53b8e98c23310294…
https://git.kernel.org/stable/c/c8eef12af1cc73031…
https://git.kernel.org/stable/c/38a69f08ee82c450d…
https://git.kernel.org/stable/c/f8488c07bea2431ee…
https://git.kernel.org/stable/c/2757ad3e4b6f9e0fe…

Impacted products

2 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)
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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JSON

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{
  "containers": {
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "fs/smb/client/cifsacl.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "lessThan": "b53b8e98c23310294fc45fc686db5ee860311896",
              "status": "affected",
              "version": "e2f8fbfb8d09c06decde162090fac3ee220aa280",
              "versionType": "git"
            },
            {
              "lessThan": "c8eef12af1cc73031639ea7cf16e0b10e2536b0b",
              "status": "affected",
              "version": "e2f8fbfb8d09c06decde162090fac3ee220aa280",
              "versionType": "git"
            },
            {
              "lessThan": "38a69f08ee82c450d3e4168707fff2e317dc3ff7",
              "status": "affected",
              "version": "e2f8fbfb8d09c06decde162090fac3ee220aa280",
              "versionType": "git"
            },
            {
              "lessThan": "f8488c07bea2431ee12a6067d736578064fa46b4",
              "status": "affected",
              "version": "e2f8fbfb8d09c06decde162090fac3ee220aa280",
              "versionType": "git"
            },
            {
              "lessThan": "2757ad3e4b6f9e0fed4c7739594e702abc5cab21",
              "status": "affected",
              "version": "e2f8fbfb8d09c06decde162090fac3ee220aa280",
              "versionType": "git"
            }
          ]
        },
        {
          "defaultStatus": "affected",
          "product": "Linux",
          "programFiles": [
            "fs/smb/client/cifsacl.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "5.4"
            },
            {
              "lessThan": "5.4",
              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.6.*",
              "status": "unaffected",
              "version": "6.6.136",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.12.*",
              "status": "unaffected",
              "version": "6.12.84",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.18.*",
              "status": "unaffected",
              "version": "6.18.25",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "7.0.*",
              "status": "unaffected",
              "version": "7.0.2",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "7.1-rc1",
              "versionType": "original_commit_for_fix"
            }
          ]
        }
      ],
      "cpeApplicability": [
        {
          "nodes": [
            {
              "cpeMatch": [
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.6.136",
                  "versionStartIncluding": "5.4",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
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                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
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                },
                {
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                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "7.1-rc1",
                  "versionStartIncluding": "5.4",
                  "vulnerable": true
                }
              ],
              "negate": false,
              "operator": "OR"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "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."
        }
      ],
      "metrics": [
        {
          "cvssV3_1": {
            "baseScore": 7.6,
            "baseSeverity": "HIGH",
            "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:L/A:H",
            "version": "3.1"
          }
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-05-11T22:22:52.597Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
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        {
          "url": "https://git.kernel.org/stable/c/b53b8e98c23310294fc45fc686db5ee860311896"
        },
        {
          "url": "https://git.kernel.org/stable/c/c8eef12af1cc73031639ea7cf16e0b10e2536b0b"
        },
        {
          "url": "https://git.kernel.org/stable/c/38a69f08ee82c450d3e4168707fff2e317dc3ff7"
        },
        {
          "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",
      "x_generator": {
        "engine": "bippy-1.2.0"
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
    "assignerShortName": "Linux",
    "cveId": "CVE-2026-43350",
    "datePublished": "2026-05-08T13:41:53.276Z",
    "dateReserved": "2026-05-01T14:12:56.003Z",
    "dateUpdated": "2026-05-11T22:22:52.597Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}

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.

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GHSA-XVVM-359F-6VGC

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

Tags

Sightings

Nomenclature