CVE-2026-63893 (GCVE-0-2026-63893)
Vulnerability from cvelistv5
Published
2026-07-19 14:55
Modified
2026-08-05 12:36
Severity ?
8.1 (High) - CVSS:3.1/AV:A/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: thunderbolt: property: Reject u32 wrap in tb_property_entry_valid() entry->value is u32 and entry->length is u16; the sum is performed in u32 and wraps. A malicious XDomain peer can pick value = 0xffffff00, length = 0x100 so the sum 0x100000000 wraps to 0 and passes the > block_len check. tb_property_parse() then passes entry->value to parse_dwdata() as a dword offset into the property block, reading attacker-directed memory far past the allocation. For TEXT-typed entries with the "deviceid" or "vendorid" keys this lands in xd->device_name / xd->vendor_name and is readable back via the per-XDomain device_name / vendor_name sysfs attributes; the leak is NUL-bounded (kstrdup() stops at the first zero byte) and untargeted (the attacker picks a delta, not an absolute address). DATA-typed entries are parsed into property->value.data but not generically surfaced to userspace. Use check_add_overflow() so a wrapped sum is rejected.
References
Impacted products
Vendor Product Version
Linux Linux Version: cdae7c07e3e3509eaabc18c1640a55dc5b99c179
Version: cdae7c07e3e3509eaabc18c1640a55dc5b99c179
Version: cdae7c07e3e3509eaabc18c1640a55dc5b99c179
Version: cdae7c07e3e3509eaabc18c1640a55dc5b99c179
Version: cdae7c07e3e3509eaabc18c1640a55dc5b99c179
Version: cdae7c07e3e3509eaabc18c1640a55dc5b99c179
Version: cdae7c07e3e3509eaabc18c1640a55dc5b99c179
Version: cdae7c07e3e3509eaabc18c1640a55dc5b99c179
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{
  "containers": {
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "drivers/thunderbolt/property.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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          "product": "Linux",
          "programFiles": [
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          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
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              "status": "affected",
              "version": "4.15"
            },
            {
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              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
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            {
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              "status": "unaffected",
              "version": "5.10.259",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "5.15.*",
              "status": "unaffected",
              "version": "5.15.210",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.1.*",
              "status": "unaffected",
              "version": "6.1.176",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.6.*",
              "status": "unaffected",
              "version": "6.6.143",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.12.*",
              "status": "unaffected",
              "version": "6.12.93",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.18.*",
              "status": "unaffected",
              "version": "6.18.35",
              "versionType": "semver"
            },
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              "lessThanOrEqual": "7.0.*",
              "status": "unaffected",
              "version": "7.0.12",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "7.1",
              "versionType": "original_commit_for_fix"
            }
          ]
        }
      ],
      "cpeApplicability": [
        {
          "nodes": [
            {
              "cpeMatch": [
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "5.10.259",
                  "versionStartIncluding": "4.15",
                  "vulnerable": true
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                  "vulnerable": true
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                  "versionStartIncluding": "4.15",
                  "vulnerable": true
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                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.6.143",
                  "versionStartIncluding": "4.15",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
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                {
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                  "versionEndExcluding": "7.1",
                  "versionStartIncluding": "4.15",
                  "vulnerable": true
                }
              ],
              "negate": false,
              "operator": "OR"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nthunderbolt: property: Reject u32 wrap in tb_property_entry_valid()\n\nentry-\u003evalue is u32 and entry-\u003elength is u16; the sum is performed in\nu32 and wraps.  A malicious XDomain peer can pick\nvalue = 0xffffff00, length = 0x100 so the sum 0x100000000 wraps to 0\nand passes the \u003e block_len check.  tb_property_parse() then passes\nentry-\u003evalue to parse_dwdata() as a dword offset into the property\nblock, reading attacker-directed memory far past the allocation.\n\nFor TEXT-typed entries with the \"deviceid\" or \"vendorid\" keys this\nlands in xd-\u003edevice_name / xd-\u003evendor_name and is readable back via\nthe per-XDomain device_name / vendor_name sysfs attributes; the leak\nis NUL-bounded (kstrdup() stops at the first zero byte) and\nuntargeted (the attacker picks a delta, not an absolute address).\nDATA-typed entries are parsed into property-\u003evalue.data but not\ngenerically surfaced to userspace.\n\nUse check_add_overflow() so a wrapped sum is rejected."
        }
      ],
      "metrics": [
        {
          "cvssV3_1": {
            "baseScore": 8.1,
            "baseSeverity": "HIGH",
            "vectorString": "CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:H",
            "version": "3.1"
          },
          "scenarios": [
            {
              "lang": "en",
              "value": "AV:A - A malicious Thunderbolt XDomain peer (adjacent host, dock, or in-line device on a direct Thunderbolt/USB4 link) delivers crafted PROPERTIES_RESPONSE data that the victim kernel parses during automatic XDomain discovery.\nAC:L - The peer fully controls property entry value/length fields and can reliably craft the u32 wrap (e.g. value=0xffffff00, length=0x100) without races or special memory layout.\nPR:N - Exploitation requires no privileges on the victim system; the attacker only needs to be the connected XDomain peer responding to the kernel-initiated property exchange, with no authentication on that control-plane path.\nUI:N - Once a Thunderbolt XDomain link exists, property fetching and parsing run automatically in the kernel handshake state machine without any additional victim user action at exploitation time.\nS:U - Impact is confined to the victim kernel/userspace boundary (kernel heap disclosure to local sysfs and possible kernel crash); it does not cross VM, IOMMU, or sandbox security boundaries.\nC:H - Integer-wrap bypass enables an out-of-bounds kernel memory read of up to entry-\u003elength dwords, which for deviceid/vendorid TEXT properties is copied into world-readable sysfs attributes, disclosing kernel heap contents.\nI:N - The bug is an out-of-bounds read via parse_dwdata(); destination buffers are properly sized kcalloc allocations, so there is no out-of-bounds write or integrity modification of victim kernel structures.\nA:H - Reading from block+0xffffff00 dwords (~4 GB past the allocation) will access unmapped kernel addresses, causing a kernel fault/oops/panic in addition to any information disclosure."
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-08-05T12:36:59.715Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "references": [
        {
          "url": "https://git.kernel.org/stable/c/6a63623621639acbb39bc2d9fb09559681716695"
        },
        {
          "url": "https://git.kernel.org/stable/c/e8a0b0a93a6ef958e70b1dd4930beb6dc0026b36"
        },
        {
          "url": "https://git.kernel.org/stable/c/9fee50c4e1e42f6d3cbe30df584f9f648f626071"
        },
        {
          "url": "https://git.kernel.org/stable/c/8d4a758b407ab3de3be86d1ceadfa35d717d30c7"
        },
        {
          "url": "https://git.kernel.org/stable/c/5c06a3043ad944f087bb2ae0aae28d820bb9f460"
        },
        {
          "url": "https://git.kernel.org/stable/c/31b98e503ecca8077e5247253dd5425ab84bc96d"
        },
        {
          "url": "https://git.kernel.org/stable/c/a47784aee77f33f786dc5d7375db821bdae68792"
        },
        {
          "url": "https://git.kernel.org/stable/c/01deda0152066c6c955f0619114ea6afa070aaec"
        }
      ],
      "title": "thunderbolt: property: Reject u32 wrap in tb_property_entry_valid()",
      "x_generator": {
        "engine": "bippy-1.2.0"
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
    "assignerShortName": "Linux",
    "cveId": "CVE-2026-63893",
    "datePublished": "2026-07-19T14:55:04.288Z",
    "dateReserved": "2026-07-19T07:54:57.019Z",
    "dateUpdated": "2026-08-05T12:36:59.715Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}


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