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

Vulnerability from cvelistv5 – Published: 2026-07-25 08:49 – Updated: 2026-08-17 04:52
VLAI
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
References
Impacted 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)
Create a notification for this product.
Linux Linux Create a notification for this product.
Show details on NVD website
To clipboard 

{
  "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": [
            {
              "lessThan": "445ece263131780dee273d727a4d6f11934feec7",
              "status": "affected",
              "version": "31c6312608c60b72a1feb99a5afb680645a3e8a3",
              "versionType": "git"
            },
            {
              "lessThan": "36bfa52459e45c0d5b668de2f1c91f6dc5c67775",
              "status": "affected",
              "version": "573e502d14714d2947e22e7eff40ec20a6a44a42",
              "versionType": "git"
            },
            {
              "lessThan": "4a9d2657d3e05f6ed09c148cb127b4e58702275f",
              "status": "affected",
              "version": "419ec1b604d7fb60c10aec2dc062371f9fcd4940",
              "versionType": "git"
            },
            {
              "lessThan": "fdafa1e68dc75045b7b617e6e7d2854950804d83",
              "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",
  "vulnerability-lookup:meta": {
    "epss": {
      "cve": "CVE-2026-64257",
      "date": "2026-08-16",
      "epss": "0.00672",
      "percentile": "0.49064"
    },
    "nvd": "{\"cve\":{\"id\":\"CVE-2026-64257\",\"sourceIdentifier\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"published\":\"2026-07-25T10:17:05.817\",\"lastModified\":\"2026-08-17T05:17:24.327\",\"vulnStatus\":\"Analyzed\",\"cveTags\":[],\"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.\"}],\"affected\":[{\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"affectedData\":[{\"vendor\":\"Linux\",\"product\":\"Linux\",\"defaultStatus\":\"unaffected\",\"programFiles\":[\"fs/smb/client/smb2misc.c\"],\"repo\":\"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git\",\"versions\":[{\"version\":\"31c6312608c60b72a1feb99a5afb680645a3e8a3\",\"lessThan\":\"445ece263131780dee273d727a4d6f11934feec7\",\"versionType\":\"git\",\"status\":\"affected\"},{\"version\":\"573e502d14714d2947e22e7eff40ec20a6a44a42\",\"lessThan\":\"36bfa52459e45c0d5b668de2f1c91f6dc5c67775\",\"versionType\":\"git\",\"status\":\"affected\"},{\"version\":\"419ec1b604d7fb60c10aec2dc062371f9fcd4940\",\"lessThan\":\"4a9d2657d3e05f6ed09c148cb127b4e58702275f\",\"versionType\":\"git\",\"status\":\"affected\"},{\"version\":\"ceb875a375dedbf51c9425c1d13a2d7a8435c08c\",\"lessThan\":\"fdafa1e68dc75045b7b617e6e7d2854950804d83\",\"versionType\":\"git\",\"status\":\"affected\"},{\"version\":\"6e9d10f62773b99bd927940fd9cbdfe7207e23ff\",\"lessThan\":\"57cba95f0e97c6f6e45e6731da30aff091bd7460\",\"versionType\":\"git\",\"status\":\"affected\"},{\"version\":\"53b7c271f06be4dd5cfc8c6ef552a8355c891a7f\",\"lessThan\":\"8986c932905ea508d66da421eb2eb6e676ace1fe\",\"versionType\":\"git\",\"status\":\"affected\"},{\"version\":\"8d0bbc78046d264bbf6a574ea6f9072258a43e35\",\"versionType\":\"git\",\"status\":\"affected\"},{\"version\":\"b6a381c01e2ac98a48e32ac0f2a45bbadd9e26b0\",\"versionType\":\"git\",\"status\":\"affected\"},{\"version\":\"5.10.261\",\"lessThan\":\"5.11\",\"versionType\":\"semver\",\"status\":\"affected\"},{\"version\":\"5.15.212\",\"lessThan\":\"5.16\",\"versionType\":\"semver\",\"status\":\"affected\"}]},{\"vendor\":\"Linux\",\"product\":\"Linux\",\"defaultStatus\":\"unaffected\",\"programFiles\":[\"fs/smb/client/smb2misc.c\"],\"repo\":\"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git\"}]}],\"metrics\":{\"cvssMetricV31\":[{\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"type\":\"Secondary\",\"cvssData\":{\"version\":\"3.1\",\"vectorString\":\"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:H\",\"baseScore\":9.1,\"baseSeverity\":\"CRITICAL\",\"attackVector\":\"NETWORK\",\"attackComplexity\":\"LOW\",\"privilegesRequired\":\"NONE\",\"userInteraction\":\"NONE\",\"scope\":\"UNCHANGED\",\"confidentialityImpact\":\"HIGH\",\"integrityImpact\":\"NONE\",\"availabilityImpact\":\"HIGH\"},\"exploitabilityScore\":3.9,\"impactScore\":5.2}]},\"weaknesses\":[{\"source\":\"nvd@nist.gov\",\"type\":\"Primary\",\"description\":[{\"lang\":\"en\",\"value\":\"NVD-CWE-noinfo\"}]}],\"configurations\":[{\"nodes\":[{\"operator\":\"OR\",\"negate\":false,\"cpeMatch\":[{\"vulnerable\":true,\"criteria\":\"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*\",\"versionStartIncluding\":\"5.10.261\",\"versionEndExcluding\":\"5.11\",\"matchCriteriaId\":\"9F5DCE07-AD23-4185-ADF1-58B212802E8C\"},{\"vulnerable\":true,\"criteria\":\"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*\",\"versionStartIncluding\":\"5.15.212\",\"versionEndExcluding\":\"5.16\",\"matchCriteriaId\":\"5597711C-7BCC-45F8-9366-7FE29BC58F2F\"},{\"vulnerable\":true,\"criteria\":\"cpe:2.3:o:linux:linux_kernel:7.2:rc3:*:*:*:*:*:*\",\"matchCriteriaId\":\"D6ECA620-8606-4230-A87D-3FF3EFE12592\"}]}]}],\"references\":[{\"url\":\"https://git.kernel.org/stable/c/36bfa52459e45c0d5b668de2f1c91f6dc5c67775\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"tags\":[\"Patch\"]},{\"url\":\"https://git.kernel.org/stable/c/445ece263131780dee273d727a4d6f11934feec7\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"tags\":[\"Patch\"]},{\"url\":\"https://git.kernel.org/stable/c/4a9d2657d3e05f6ed09c148cb127b4e58702275f\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"tags\":[\"Patch\"]},{\"url\":\"https://git.kernel.org/stable/c/57cba95f0e97c6f6e45e6731da30aff091bd7460\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"tags\":[\"Patch\"]},{\"url\":\"https://git.kernel.org/stable/c/8986c932905ea508d66da421eb2eb6e676ace1fe\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"tags\":[\"Patch\"]},{\"url\":\"https://git.kernel.org/stable/c/fdafa1e68dc75045b7b617e6e7d2854950804d83\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"tags\":[\"Patch\"]}]}}",
    "redhat_vex": {
      "aggregate_severity": "None",
      "current_release_date": "2026-07-29T13:24:48+00:00",
      "cve": "CVE-2026-64257",
      "id": "CVE-2026-64257",
      "initial_release_date": "2026-07-25T00:00:00+00:00",
      "product_status:known_not_affected": "274",
      "source": "Red Hat CSAF VEX",
      "status": "final",
      "title": "kernel: smb: client: reject overlapping data areas in SMB2 responses",
      "url": "https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-64257.json",
      "version": "3"
    },
    "suse_vex": {
      "aggregate_severity": "important",
      "current_release_date": "2026-08-03T17:14:39Z",
      "cve": "CVE-2026-64257",
      "id": "CVE-2026-64257",
      "initial_release_date": "2026-07-25T16:47:10Z",
      "product_status:known_not_affected": "298",
      "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": "4"
    }
  }
}



Log in or create an account to share your comment.




Tags
Taxonomy of the tags.





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.