Vulnerability-Lookup

FKIE_CVE-2026-64391

Vulnerability from fkie_nvd - Published: 2026-07-25 10:17 - Updated: 2026-07-27 05:16

Severity

9.8 (Critical) - CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Summary

In the Linux kernel, the following vulnerability has been resolved: ksmbd: use opener credentials for ADS I/O Alternate data streams are stored as xattrs. Unlike regular file I/O, their read and write paths therefore call VFS xattr helpers which recheck inode permissions and LSM policy using the current task credentials. Run ADS I/O with the credentials captured when the SMB handle was opened.

References

	URL	Tags
	416baaa9-dc9f-4396-8d5f-8c081fb06d67	https://git.kernel.org/stable/c/2b4592cea214683de0f2ce6f8c22c097fb0ea1ab
	416baaa9-dc9f-4396-8d5f-8c081fb06d67	https://git.kernel.org/stable/c/52a56cf53ec834c44ac1b4d16d585f26613ee5ce
	416baaa9-dc9f-4396-8d5f-8c081fb06d67	https://git.kernel.org/stable/c/a8f5d39971bbad9340d49cd41b0e2da9452a649d
	416baaa9-dc9f-4396-8d5f-8c081fb06d67	https://git.kernel.org/stable/c/baa5e094886fffa7e6272edcb5e08be5ce28262c

Impacted products

	Vendor	Product	Version

JSON

To clipboard

{
  "affected": [
    {
      "affectedData": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "fs/smb/server/vfs.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "lessThan": "a8f5d39971bbad9340d49cd41b0e2da9452a649d",
              "status": "affected",
              "version": "f44158485826c076335d6860d35872271a83791d",
              "versionType": "git"
            },
            {
              "lessThan": "2b4592cea214683de0f2ce6f8c22c097fb0ea1ab",
              "status": "affected",
              "version": "f44158485826c076335d6860d35872271a83791d",
              "versionType": "git"
            },
            {
              "lessThan": "52a56cf53ec834c44ac1b4d16d585f26613ee5ce",
              "status": "affected",
              "version": "f44158485826c076335d6860d35872271a83791d",
              "versionType": "git"
            },
            {
              "lessThan": "baa5e094886fffa7e6272edcb5e08be5ce28262c",
              "status": "affected",
              "version": "f44158485826c076335d6860d35872271a83791d",
              "versionType": "git"
            }
          ]
        },
        {
          "defaultStatus": "affected",
          "product": "Linux",
          "programFiles": [
            "fs/smb/server/vfs.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "5.15"
            },
            {
              "lessThan": "5.15",
              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.12.*",
              "status": "unaffected",
              "version": "6.12.96",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.18.*",
              "status": "unaffected",
              "version": "6.18.39",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "7.1.*",
              "status": "unaffected",
              "version": "7.1.4",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "7.2-rc1",
              "versionType": "original_commit_for_fix"
            }
          ]
        }
      ],
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    }
  ],
  "cveTags": [],
  "descriptions": [
    {
      "lang": "en",
      "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nksmbd: use opener credentials for ADS I/O\n\nAlternate data streams are stored as xattrs. Unlike regular file I/O,\ntheir read and write paths therefore call VFS xattr helpers which recheck\ninode permissions and LSM policy using the current task credentials.\n\nRun ADS I/O with the credentials captured when the SMB handle was opened."
    }
  ],
  "id": "CVE-2026-64391",
  "lastModified": "2026-07-27T05:16:45.943",
  "metrics": {
    "cvssMetricV31": [
      {
        "cvssData": {
          "attackComplexity": "LOW",
          "attackVector": "NETWORK",
          "availabilityImpact": "HIGH",
          "baseScore": 9.8,
          "baseSeverity": "CRITICAL",
          "confidentialityImpact": "HIGH",
          "integrityImpact": "HIGH",
          "privilegesRequired": "NONE",
          "scope": "UNCHANGED",
          "userInteraction": "NONE",
          "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H",
          "version": "3.1"
        },
        "exploitabilityScore": 3.9,
        "impactScore": 5.9,
        "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "type": "Secondary"
      }
    ]
  },
  "published": "2026-07-25T10:17:22.453",
  "references": [
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/2b4592cea214683de0f2ce6f8c22c097fb0ea1ab"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/52a56cf53ec834c44ac1b4d16d585f26613ee5ce"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/a8f5d39971bbad9340d49cd41b0e2da9452a649d"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/baa5e094886fffa7e6272edcb5e08be5ce28262c"
    }
  ],
  "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
  "vulnStatus": "Received"
}

CVE-2026-64391 (GCVE-0-2026-64391)

Vulnerability from cvelistv5 – Published: 2026-07-25 08:50 – Updated: 2026-08-05 12:41

Title

ksmbd: use opener credentials for ADS I/O

Summary

Severity

9.8 (Critical)


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

Assigner

Linux

References

4 references

URL	Tags
https://git.kernel.org/stable/c/a8f5d39971bbad934…
https://git.kernel.org/stable/c/2b4592cea214683de…
https://git.kernel.org/stable/c/52a56cf53ec834c44…
https://git.kernel.org/stable/c/baa5e094886fffa7e…

Impacted products

2 products

Vendor	Product	Version
Linux	Linux	Affected: f44158485826c076335d6860d35872271a83791d , < a8f5d39971bbad9340d49cd41b0e2da9452a649d (git) Affected: f44158485826c076335d6860d35872271a83791d , < 2b4592cea214683de0f2ce6f8c22c097fb0ea1ab (git) Affected: f44158485826c076335d6860d35872271a83791d , < 52a56cf53ec834c44ac1b4d16d585f26613ee5ce (git) Affected: f44158485826c076335d6860d35872271a83791d , < baa5e094886fffa7e6272edcb5e08be5ce28262c (git)
Linux	Linux	Affected: 5.15 Unaffected: 0 , < 5.15 (semver) Unaffected: 6.12.96 , ≤ 6.12.* (semver) Unaffected: 6.18.39 , ≤ 6.18.* (semver) Unaffected: 7.1.4 , ≤ 7.1.* (semver) Unaffected: 7.2-rc1 , ≤ * (original_commit_for_fix)

Show details on NVD website

JSON

To clipboard

{
  "containers": {
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "fs/smb/server/vfs.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "lessThan": "a8f5d39971bbad9340d49cd41b0e2da9452a649d",
              "status": "affected",
              "version": "f44158485826c076335d6860d35872271a83791d",
              "versionType": "git"
            },
            {
              "lessThan": "2b4592cea214683de0f2ce6f8c22c097fb0ea1ab",
              "status": "affected",
              "version": "f44158485826c076335d6860d35872271a83791d",
              "versionType": "git"
            },
            {
              "lessThan": "52a56cf53ec834c44ac1b4d16d585f26613ee5ce",
              "status": "affected",
              "version": "f44158485826c076335d6860d35872271a83791d",
              "versionType": "git"
            },
            {
              "lessThan": "baa5e094886fffa7e6272edcb5e08be5ce28262c",
              "status": "affected",
              "version": "f44158485826c076335d6860d35872271a83791d",
              "versionType": "git"
            }
          ]
        },
        {
          "defaultStatus": "affected",
          "product": "Linux",
          "programFiles": [
            "fs/smb/server/vfs.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "5.15"
            },
            {
              "lessThan": "5.15",
              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.12.*",
              "status": "unaffected",
              "version": "6.12.96",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.18.*",
              "status": "unaffected",
              "version": "6.18.39",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "7.1.*",
              "status": "unaffected",
              "version": "7.1.4",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "7.2-rc1",
              "versionType": "original_commit_for_fix"
            }
          ]
        }
      ],
      "cpeApplicability": [
        {
          "nodes": [
            {
              "cpeMatch": [
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.12.96",
                  "versionStartIncluding": "5.15",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.18.39",
                  "versionStartIncluding": "5.15",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "7.1.4",
                  "versionStartIncluding": "5.15",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "7.2-rc1",
                  "versionStartIncluding": "5.15",
                  "vulnerable": true
                }
              ],
              "negate": false,
              "operator": "OR"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nksmbd: use opener credentials for ADS I/O\n\nAlternate data streams are stored as xattrs. Unlike regular file I/O,\ntheir read and write paths therefore call VFS xattr helpers which recheck\ninode permissions and LSM policy using the current task credentials.\n\nRun ADS I/O with the credentials captured when the SMB handle was opened."
        }
      ],
      "metrics": [
        {
          "cvssV3_1": {
            "baseScore": 9.8,
            "baseSeverity": "CRITICAL",
            "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H",
            "version": "3.1"
          },
          "scenarios": [
            {
              "lang": "en",
              "value": "AV:N - An attacker reaches the vulnerable ADS read and write paths through SMB2 requests to an exposed ksmbd server over TCP/445.\nAC:L - Exploitation is deterministic using an ADS handle followed by ordinary SMB2 READ or WRITE requests; no race, memory-layout dependency, or condition outside the attacker\u0027s control is required.\nPR:N - Although a valid session, tree connection, and handle are required, a guest-enabled streams share permits a remote client to establish the necessary guest session without supplying valid credentials.\nUI:N - The attacker directly opens and accesses the alternate data stream through SMB requests without requiring any victim action.\nS:U - The credential bypass affects ADS data managed by the same host kernel and filesystem security authority; it does not cross a virtualization or comparable isolation boundary.\nC:H - Privileged worker credentials can bypass inode and LSM xattr checks and disclose the complete contents of an attacker-selected named stream, including potentially sensitive application data.\nI:H - The vulnerable write path can bypass xattr authorization and replace or truncate the complete named stream with attacker-controlled data.\nA:H - Repeated unauthorized truncation or corruption can persistently destroy an ADS and render applications or services that depend on that stream unusable until the data is restored."
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-08-05T12:41:28.361Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "references": [
        {
          "url": "https://git.kernel.org/stable/c/a8f5d39971bbad9340d49cd41b0e2da9452a649d"
        },
        {
          "url": "https://git.kernel.org/stable/c/2b4592cea214683de0f2ce6f8c22c097fb0ea1ab"
        },
        {
          "url": "https://git.kernel.org/stable/c/52a56cf53ec834c44ac1b4d16d585f26613ee5ce"
        },
        {
          "url": "https://git.kernel.org/stable/c/baa5e094886fffa7e6272edcb5e08be5ce28262c"
        }
      ],
      "title": "ksmbd: use opener credentials for ADS I/O",
      "x_generator": {
        "engine": "bippy-1.2.0"
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
    "assignerShortName": "Linux",
    "cveId": "CVE-2026-64391",
    "datePublished": "2026-07-25T08:50:38.013Z",
    "dateReserved": "2026-07-19T15:36:31.785Z",
    "dateUpdated": "2026-08-05T12:41:28.361Z",
    "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.

The MITRE ATT&CK techniques below are AI-generated suggestions, inferred from the description of the vulnerability by the CIRCL/vulnerability-attack-technique-classification-roberta-base model, served locally by ML-Gateway. They have not been verified by an analyst and are provided for guidance only.

Action not permitted

FKIE_CVE-2026-64391

CVE-2026-64391 (GCVE-0-2026-64391)

Tags

Sightings

Nomenclature