CVE-2026-64257 (GCVE-0-2026-64257)
Vulnerability from cvelistv5
Published
2026-07-25 08:49
Modified
2026-08-17 04:52
Severity ?
9.1 (Critical) - CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:H
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.
References
Impacted products
Vendor Product Version
Linux Linux Version: 31c6312608c60b72a1feb99a5afb680645a3e8a3
Version: 573e502d14714d2947e22e7eff40ec20a6a44a42
Version: 419ec1b604d7fb60c10aec2dc062371f9fcd4940
Version: ceb875a375dedbf51c9425c1d13a2d7a8435c08c
Version: 6e9d10f62773b99bd927940fd9cbdfe7207e23ff
Version: 53b7c271f06be4dd5cfc8c6ef552a8355c891a7f
Version: 8d0bbc78046d264bbf6a574ea6f9072258a43e35
Version: b6a381c01e2ac98a48e32ac0f2a45bbadd9e26b0
Version: 5.10.261   ≤
Version: 5.15.212   ≤
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{
  "containers": {
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "fs/smb/client/smb2misc.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
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              "status": "affected",
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              "versionType": "git"
            },
            {
              "lessThan": "36bfa52459e45c0d5b668de2f1c91f6dc5c67775",
              "status": "affected",
              "version": "573e502d14714d2947e22e7eff40ec20a6a44a42",
              "versionType": "git"
            },
            {
              "lessThan": "4a9d2657d3e05f6ed09c148cb127b4e58702275f",
              "status": "affected",
              "version": "419ec1b604d7fb60c10aec2dc062371f9fcd4940",
              "versionType": "git"
            },
            {
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              "status": "affected",
              "version": "ceb875a375dedbf51c9425c1d13a2d7a8435c08c",
              "versionType": "git"
            },
            {
              "lessThan": "57cba95f0e97c6f6e45e6731da30aff091bd7460",
              "status": "affected",
              "version": "6e9d10f62773b99bd927940fd9cbdfe7207e23ff",
              "versionType": "git"
            },
            {
              "lessThan": "8986c932905ea508d66da421eb2eb6e676ace1fe",
              "status": "affected",
              "version": "53b7c271f06be4dd5cfc8c6ef552a8355c891a7f",
              "versionType": "git"
            },
            {
              "status": "affected",
              "version": "8d0bbc78046d264bbf6a574ea6f9072258a43e35",
              "versionType": "git"
            },
            {
              "status": "affected",
              "version": "b6a381c01e2ac98a48e32ac0f2a45bbadd9e26b0",
              "versionType": "git"
            },
            {
              "lessThan": "5.11",
              "status": "affected",
              "version": "5.10.261",
              "versionType": "semver"
            },
            {
              "lessThan": "5.16",
              "status": "affected",
              "version": "5.15.212",
              "versionType": "semver"
            }
          ]
        },
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "fs/smb/client/smb2misc.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux"
        }
      ],
      "cpeApplicability": [
        {
          "nodes": [
            {
              "cpeMatch": [
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionStartIncluding": "5.10.261",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionStartIncluding": "5.15.212",
                  "vulnerable": true
                }
              ],
              "negate": false,
              "operator": "OR"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "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."
        }
      ],
      "metrics": [
        {
          "cvssV3_1": {
            "baseScore": 9.1,
            "baseSeverity": "CRITICAL",
            "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:H",
            "version": "3.1"
          },
          "scenarios": [
            {
              "lang": "en",
              "value": "AV:N - A malicious or compromised SMB server can deliver the crafted SMB2 response over TCP during client negotiation.\nAC:L - The overlapping offset and oversized length are attacker-controlled and deterministically bypass validation; no race or uncontrolled memory layout is required to trigger the out-of-bounds read.\nPR:N - The vulnerable NEGOTIATE response is processed before SMB authentication or signature verification, requiring no privileges or credentials on the target.\nUI:N - An already configured SMB mount can negotiate during automatic mounting or reconnection without a human opening crafted content.\nS:U - The vulnerable parser and the affected kernel memory remain within the Linux kernel\u0027s security authority.\nC:H - The validation mismatch permits an attacker-controlled ASN.1 length to read far beyond the 448-byte receive object, potentially traversing tens of kilobytes of adjacent kernel memory.\nI:N - The investigated paths provide an out-of-bounds read but no out-of-bounds write, use-after-free, type confusion, or other arbitrary modification primitive.\nA:H - The slab out-of-bounds access is repeatable and can produce a kernel fault or panic, particularly on hardened or memory-safety-instrumented deployments."
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-08-17T04:52:09.787Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "references": [
        {
          "url": "https://git.kernel.org/stable/c/445ece263131780dee273d727a4d6f11934feec7"
        },
        {
          "url": "https://git.kernel.org/stable/c/36bfa52459e45c0d5b668de2f1c91f6dc5c67775"
        },
        {
          "url": "https://git.kernel.org/stable/c/4a9d2657d3e05f6ed09c148cb127b4e58702275f"
        },
        {
          "url": "https://git.kernel.org/stable/c/fdafa1e68dc75045b7b617e6e7d2854950804d83"
        },
        {
          "url": "https://git.kernel.org/stable/c/57cba95f0e97c6f6e45e6731da30aff091bd7460"
        },
        {
          "url": "https://git.kernel.org/stable/c/8986c932905ea508d66da421eb2eb6e676ace1fe"
        }
      ],
      "title": "smb: client: reject overlapping data areas in SMB2 responses",
      "x_generator": {
        "engine": "bippy-1.2.0"
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
    "assignerShortName": "Linux",
    "cveId": "CVE-2026-64257",
    "datePublished": "2026-07-25T08:49:09.345Z",
    "dateReserved": "2026-07-19T15:36:31.773Z",
    "dateUpdated": "2026-08-17T04:52:09.787Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}


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