CVE-2026-43334 (GCVE-0-2026-43334)
Vulnerability from cvelistv5
Published
2026-05-08 13:31
Modified
2026-08-05 12:27
Severity ?
8.8 (High) - CVSS:3.1/AV:A/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: Bluetooth: SMP: force responder MITM requirements before building the pairing response smp_cmd_pairing_req() currently builds the pairing response from the initiator auth_req before enforcing the local BT_SECURITY_HIGH requirement. If the initiator omits SMP_AUTH_MITM, the response can also omit it even though the local side still requires MITM. tk_request() then sees an auth value without SMP_AUTH_MITM and may select JUST_CFM, making method selection inconsistent with the pairing policy the responder already enforces. When the local side requires HIGH security, first verify that MITM can be achieved from the IO capabilities and then force SMP_AUTH_MITM in the response in both rsp.auth_req and auth. This keeps the responder auth bits and later method selection aligned.
References
Impacted products
Vendor Product Version
Linux Linux Version: 2b64d153a0cc9d2b60e47be013cde8490f16e0a5
Version: 2b64d153a0cc9d2b60e47be013cde8490f16e0a5
Version: 2b64d153a0cc9d2b60e47be013cde8490f16e0a5
Version: 2b64d153a0cc9d2b60e47be013cde8490f16e0a5
Version: 2b64d153a0cc9d2b60e47be013cde8490f16e0a5
Version: 2b64d153a0cc9d2b60e47be013cde8490f16e0a5
Version: 2b64d153a0cc9d2b60e47be013cde8490f16e0a5
Version: 2b64d153a0cc9d2b60e47be013cde8490f16e0a5
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{
  "containers": {
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "net/bluetooth/smp.c"
          ],
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          "vendor": "Linux",
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          "vendor": "Linux",
          "versions": [
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              "version": "0",
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              "version": "5.10.253",
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              "version": "6.1.168",
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              "status": "unaffected",
              "version": "6.12.81",
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              "status": "unaffected",
              "version": "6.18.22",
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              "status": "unaffected",
              "version": "6.19.12",
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            },
            {
              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "7.0",
              "versionType": "original_commit_for_fix"
            }
          ]
        }
      ],
      "cpeApplicability": [
        {
          "nodes": [
            {
              "cpeMatch": [
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                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "5.10.253",
                  "versionStartIncluding": "3.3",
                  "vulnerable": true
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                  "vulnerable": true
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              ],
              "negate": false,
              "operator": "OR"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nBluetooth: SMP: force responder MITM requirements before building the pairing response\n\nsmp_cmd_pairing_req() currently builds the pairing response from the\ninitiator auth_req before enforcing the local BT_SECURITY_HIGH\nrequirement. If the initiator omits SMP_AUTH_MITM, the response can\nalso omit it even though the local side still requires MITM.\n\ntk_request() then sees an auth value without SMP_AUTH_MITM and may\nselect JUST_CFM, making method selection inconsistent with the pairing\npolicy the responder already enforces.\n\nWhen the local side requires HIGH security, first verify that MITM can\nbe achieved from the IO capabilities and then force SMP_AUTH_MITM in the\nresponse in both rsp.auth_req and auth. This keeps the responder auth bits\nand later method selection aligned."
        }
      ],
      "metrics": [
        {
          "cvssV3_1": {
            "baseScore": 8.8,
            "baseSeverity": "HIGH",
            "vectorString": "CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H",
            "version": "3.1"
          },
          "scenarios": [
            {
              "lang": "en",
              "value": "AV:A - The vulnerable SMP pairing responder path is reached by Bluetooth LE SMP packets from a nearby Bluetooth peer over the fixed L2CAP SMP channel, so exploitation requires adjacent radio proximity rather than IP network or local system access.\nAC:L - An attacker controls the pairing request authentication bits and IO capability fields needed to trigger the mismatch; no race, heap shaping, or condition outside the attacker\u2019s practical control is required beyond the target requiring high Bluetooth security.\nPR:N - The pairing request is processed pre-authentication and is allowed to create the SMP context, so the adjacent attacker needs no existing pairing, credentials, or local privileges.\nUI:N - The vulnerable policy decision is made during the protocol handshake initiated by the remote Bluetooth peer; in reasonable headless or auto-pairing deployments no specific victim user action is required.\nS:U - The bug bypasses Bluetooth security policy enforced by the same kernel/host Bluetooth security authority and does not cross a VM, IOMMU, or comparable scope boundary.\nC:H - By omitting MITM while the responder requires high security, an adjacent attacker can downgrade protected pairing and expose traffic or keys for services that expected authenticated Bluetooth security, giving access to sensitive protected data.\nI:H - The same downgrade can allow an attacker to inject or alter traffic on Bluetooth services that require authenticated pairing, including high-impact embedded or control deployments.\nA:H - With access to a high-security Bluetooth control channel, an attacker can plausibly disrupt protected device or service operation in embedded, industrial, automotive, or IoT deployments, producing high availability impact."
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-08-05T12:27:18.528Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "references": [
        {
          "url": "https://git.kernel.org/stable/c/425a22c5373d4e1b46492ab869074ebeeade61f3"
        },
        {
          "url": "https://git.kernel.org/stable/c/7ab69426e7ecbd18a222ee2ec87ca612d30197d7"
        },
        {
          "url": "https://git.kernel.org/stable/c/01bb4045d2306c266178f49ce0c3576d237a3040"
        },
        {
          "url": "https://git.kernel.org/stable/c/91649c02c1baaa18cedf7fb425fa1f0f852c8183"
        },
        {
          "url": "https://git.kernel.org/stable/c/c8ff0ca6508535bccabd81c5c9dcc63de8a3d4fb"
        },
        {
          "url": "https://git.kernel.org/stable/c/fa14e0e19820b1bbdb42185c9c4efa950bcffef9"
        },
        {
          "url": "https://git.kernel.org/stable/c/ec17efb1ef91506cfd17a77692eaf4bbacb520ea"
        },
        {
          "url": "https://git.kernel.org/stable/c/d05111bfe37bfd8bd4d2dfe6675d6bdeef43f7c7"
        }
      ],
      "title": "Bluetooth: SMP: force responder MITM requirements before building the pairing response",
      "x_generator": {
        "engine": "bippy-1.2.0"
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
    "assignerShortName": "Linux",
    "cveId": "CVE-2026-43334",
    "datePublished": "2026-05-08T13:31:20.923Z",
    "dateReserved": "2026-05-01T14:12:56.002Z",
    "dateUpdated": "2026-08-05T12:27:18.528Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}


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