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Bluetooth: SMP: derive legacy responder STK authentication from MITM state

Type: advisorySource: Official CVE List1 source record

In the Linux kernel, the following vulnerability has been resolved: Bluetooth: SMP: derive legacy responder STK authentication from MITM state The legacy responder path in smp_random() currently labels the stored STK as authenticated whenever pending_sec_level is BT_SECURITY_HIGH. That reflects what the local service requested, not what the pairing flow actually achieved. For Just Works/Confirm legacy pairing, SMP_FLAG_MITM_AUTH stays clear and the resulting STK should remain unauthenticated even if the local side requested HIGH security. Use the established MITM state when storing the responder STK so the key metadata matches the pairing result. This also keeps the legacy path aligned with the Secure Connections code, which already treats JUST_WORKS/JUST_CFM as unauthenticated.

Announced Group revision 1
Original source ↗

CVE-2026-31773

Primary source · Revision 1

Imported from structured advisory data. Source references identify upstream records or fields; verify affected versions and your deployed configuration.

Security context

Source reference: cve:CVE-2026-31773

Linux

Source reference: /containers/cna/affected/0/product

Affected versions
Not stated in this record
Fixed versions
Not stated in this record
Prerequisites
Not stated in this record

Linux

Source reference: /containers/cna/affected/1/product

Affected versions
Not stated in this record
Fixed versions
Not stated in this record
Prerequisites
Not stated in this record

Structured affected-version data

Original package identities and version rules from this source.

[
  {
    "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
    "vendor": "Linux",
    "product": "Linux",
    "versions": [
      {
        "status": "affected",
        "version": "fff3490f47810e2d34b91fb9e31103e923b11c2f",
        "lessThan": "9a38659a3d06080715691bd3139f9c4b61f688e3",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "fff3490f47810e2d34b91fb9e31103e923b11c2f",
        "lessThan": "667f44f1392df6482483756458c48670e579e9ff",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "fff3490f47810e2d34b91fb9e31103e923b11c2f",
        "lessThan": "929db734d12db41ca5f95424db4612397f1bd4a7",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "fff3490f47810e2d34b91fb9e31103e923b11c2f",
        "lessThan": "b1c6a8e554a39b222c0879a288ea98e338fc4d77",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "fff3490f47810e2d34b91fb9e31103e923b11c2f",
        "lessThan": "0afc846bd80073ffcd2b8040f2b2fafaea3d9f72",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "fff3490f47810e2d34b91fb9e31103e923b11c2f",
        "lessThan": "061ee71ac6b03c9f8432fe49538c3682bfcf4cf3",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "fff3490f47810e2d34b91fb9e31103e923b11c2f",
        "lessThan": "9a6d0db176f082685e0b6149700c0baf3ce2aa8b",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "fff3490f47810e2d34b91fb9e31103e923b11c2f",
        "lessThan": "20756fec2f0108cb88e815941f1ffff88dc286fe",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "14ec593d6bb050cf40a4ade2f9ac9ca050e0412c",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "3.15.5",
        "lessThan": "3.16",
        "versionType": "semver"
      }
    ],
    "programFiles": [
      "net/bluetooth/smp.c"
    ],
    "defaultStatus": "unaffected"
  },
  {
    "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
    "vendor": "Linux",
    "product": "Linux",
    "versions": [
      {
        "status": "affected",
        "version": "3.16"
      },
      {
        "status": "unaffected",
        "version": "0",
        "lessThan": "3.16",
        "versionType": "semver"
      },
      {
        "status": "unaffected",
        "version": "5.10.253",
        "versionType": "semver",
        "lessThanOrEqual": "5.10.*"
      },
      {
        "status": "unaffected",
        "version": "5.15.203",
        "versionType": "semver",
        "lessThanOrEqual": "5.15.*"
      },
      {
        "status": "unaffected",
        "version": "6.1.168",
        "versionType": "semver",
        "lessThanOrEqual": "6.1.*"
      },
      {
        "status": "unaffected",
        "version": "6.6.134",
        "versionType": "semver",
        "lessThanOrEqual": "6.6.*"
      },
      {
        "status": "unaffected",
        "version": "6.12.81",
        "versionType": "semver",
        "lessThanOrEqual": "6.12.*"
      },
      {
        "status": "unaffected",
        "version": "6.18.22",
        "versionType": "semver",
        "lessThanOrEqual": "6.18.*"
      },
      {
        "status": "unaffected",
        "version": "6.19.12",
        "versionType": "semver",
        "lessThanOrEqual": "6.19.*"
      },
      {
        "status": "unaffected",
        "version": "7.0",
        "versionType": "original_commit_for_fix",
        "lessThanOrEqual": "*"
      }
    ],
    "programFiles": [
      "net/bluetooth/smp.c"
    ],
    "defaultStatus": "affected"
  }
]
Related CVEs
CVE-2026-31773

Source reference: /cveMetadata/cveId

Publisher severity

high

Source reference: /containers/cna/metrics

Event
#39994 · Revision 1
Added to Heist Feed
Publisher date
Read the original announcement

Revision history

  1. CVE-2026-31773 · Revision 1Source updated