Vulnerability-Lookup

CVE-2026-64257 (GCVE-0-2026-64257)

Vulnerability from cvelistv5 – Published: 2026-07-25 08:49 – Updated: 2026-07-27 04:59

Title

smb: client: reject overlapping data areas in SMB2 responses

Summary

In the Linux kernel, the following vulnerability has been resolved: smb: client: reject overlapping data areas in SMB2 responses Commit 53b7c271f06b ("smb: client: restrict implied bcc[0] exemption to responses without data area") restricted the implied bcc[0] length exception to responses without a data area. However, the overlap handling in __smb2_calc_size() clears data_length, which can make an invalid response appear to have no data area and so qualify for the exception. Track data area overlap separately and reject such responses before applying the length compatibility exceptions.

Severity

9.1 (Critical)


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

Assigner

Linux

References

6 references

URL	Tags
https://git.kernel.org/stable/c/445ece263131780de…
https://git.kernel.org/stable/c/36bfa52459e45c0d5…
https://git.kernel.org/stable/c/4a9d2657d3e05f6ed…
https://git.kernel.org/stable/c/fdafa1e68dc75045b…
https://git.kernel.org/stable/c/57cba95f0e97c6f6e…
https://git.kernel.org/stable/c/8986c932905ea508d…

Impacted products

2 products

Vendor	Product	Version
Linux	Linux	Affected: 31c6312608c60b72a1feb99a5afb680645a3e8a3 , < 445ece263131780dee273d727a4d6f11934feec7 (git) Affected: 573e502d14714d2947e22e7eff40ec20a6a44a42 , < 36bfa52459e45c0d5b668de2f1c91f6dc5c67775 (git) Affected: 419ec1b604d7fb60c10aec2dc062371f9fcd4940 , < 4a9d2657d3e05f6ed09c148cb127b4e58702275f (git) Affected: ceb875a375dedbf51c9425c1d13a2d7a8435c08c , < fdafa1e68dc75045b7b617e6e7d2854950804d83 (git) Affected: 6e9d10f62773b99bd927940fd9cbdfe7207e23ff , < 57cba95f0e97c6f6e45e6731da30aff091bd7460 (git) Affected: 53b7c271f06be4dd5cfc8c6ef552a8355c891a7f , < 8986c932905ea508d66da421eb2eb6e676ace1fe (git) Affected: 8d0bbc78046d264bbf6a574ea6f9072258a43e35 (git) Affected: b6a381c01e2ac98a48e32ac0f2a45bbadd9e26b0 (git) Affected: 5.10.261 , < 5.11 (semver) Affected: 5.15.212 , < 5.16 (semver)
Linux	Linux	Affected: 7.2-rc3 Unaffected: 0 , < 7.2-rc3 (semver) Unaffected: 7.2-rc4 , ≤ * (original_commit_for_fix)

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{
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        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "fs/smb/client/smb2misc.c"
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        }
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    "datePublished": "2026-07-25T08:49:09.345Z",
    "dateReserved": "2026-07-19T15:36:31.773Z",
    "dateUpdated": "2026-07-27T04:59:11.315Z",
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    "suse_vex": {
      "aggregate_severity": "not set",
      "current_release_date": "2026-07-25T16:47:10Z",
      "cve": "CVE-2026-64257",
      "id": "CVE-2026-64257",
      "initial_release_date": "2026-07-25T16:47:10Z",
      "source": "SUSE CSAF VEX",
      "status": "interim",
      "title": "SUSE CVE CVE-2026-64257",
      "url": "https://ftp.suse.com/pub/projects/security/csaf-vex/cve-2026-64257.json",
      "version": "2"
    }
  }
}

GHSA-CFRM-7RJV-HJ84

Vulnerability from github – Published: 2026-07-25 12:31 – Updated: 2026-07-27 06:30

Details

In the Linux kernel, the following vulnerability has been resolved:

smb: client: reject overlapping data areas in SMB2 responses

Commit 53b7c271f06b ("smb: client: restrict implied bcc[0] exemption to responses without data area") restricted the implied bcc[0] length exception to responses without a data area. However, the overlap handling in __smb2_calc_size() clears data_length, which can make an invalid response appear to have no data area and so qualify for the exception.

Track data area overlap separately and reject such responses before applying the length compatibility exceptions.

Severity

9.1 (Critical)


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

Show details on source website

JSON

To clipboard

{
  "affected": [],
  "aliases": [
    "CVE-2026-64257"
  ],
  "database_specific": {
    "cwe_ids": [],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2026-07-25T10:17:05Z",
    "severity": "CRITICAL"
  },
  "details": "In the Linux kernel, the following vulnerability has been resolved:\n\nsmb: client: reject overlapping data areas in SMB2 responses\n\nCommit 53b7c271f06b (\"smb: client: restrict implied bcc[0] exemption to\nresponses without data area\") restricted the implied bcc[0] length\nexception to responses without a data area. However, the overlap\nhandling in __smb2_calc_size() clears data_length, which can make an\ninvalid response appear to have no data area and so qualify for the\nexception.\n\nTrack data area overlap separately and reject such responses before\napplying the length compatibility exceptions.",
  "id": "GHSA-cfrm-7rjv-hj84",
  "modified": "2026-07-27T06:30:31Z",
  "published": "2026-07-25T12:31:27Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-64257"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/36bfa52459e45c0d5b668de2f1c91f6dc5c67775"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/445ece263131780dee273d727a4d6f11934feec7"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/4a9d2657d3e05f6ed09c148cb127b4e58702275f"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/57cba95f0e97c6f6e45e6731da30aff091bd7460"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/8986c932905ea508d66da421eb2eb6e676ace1fe"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/fdafa1e68dc75045b7b617e6e7d2854950804d83"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:H",
      "type": "CVSS_V3"
    }
  ]
}

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

CVE-2026-64257 (GCVE-0-2026-64257)

GHSA-CFRM-7RJV-HJ84

Tags

Sightings

Nomenclature