FKIE_CVE-2026-80683

Vulnerability from fkie_nvd - Published: 2026-08-28 08:16 - Updated: 2026-10-16 20:18
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: SCO: give the socket its own sco_conn reference sco_conn_del() drops a reference it does not own. It takes one transient reference via sco_conn_hold_unless_zero() and releases it with the sco_conn_put() that follows sco_sock_hold(); the additional put in the !sk branch releases a second one: conn = sco_conn_hold_unless_zero(conn); ... sk = sco_sock_hold(conn); sco_conn_unlock(conn); sco_conn_put(conn); if (!sk) { sco_conn_put(conn); return; } When close() races the controller's Disconnection Complete, sco_chan_del() clears conn->sk and drops the socket's reference while sco_conn_del() is running. sco_conn_del() then sees sk == NULL, its own put drops the count to zero and frees the conn, and the second put writes to the freed kref: BUG: KASAN: slab-use-after-free in sco_conn_put.part.0+0x1a/0x190 Write of size 4 at addr ffff8881099dec74 by task kworker/u17:3/413 Workqueue: hci1 hci_rx_work Call Trace: sco_conn_put.part.0+0x1a/0x190 hci_disconn_complete_evt+0x1ee/0x3e0 hci_event_packet+0x54a/0x650 hci_rx_work+0x321/0x3d0 Allocated by task 413: sco_conn_add+0x72/0x1a0 sco_connect_cfm+0x88/0x670 Freed by task 413: sco_conn_del.isra.0+0x3f/0xf0 hci_disconn_complete_evt+0x1ee/0x3e0 refcount_t: underflow; use-after-free. The root cause is that the socket stores the connection without holding a reference of its own. __sco_chan_add() does: sco_pi(sk)->conn = conn; so the socket borrows whatever reference its caller happened to hold, and the callers paper over that with ad-hoc holds and puts. Give the socket a counted reference instead: __sco_chan_add() takes one and it is released together with the channel (sco_chan_del()) and in sco_sock_destruct(). With the socket holding its own reference, sco_conn_del() no longer needs the extra put and the redundant hold in sco_conn_ready() goes away. Making the socket own its reference means the connection is now actually freed on the error paths of sco_connect() where it used to leak, which in turn runs sco_conn_free() and its hci_conn_drop(conn->hcon). To keep the hci_conn accounting balanced, make that ownership explicit as well: sco_conn_add() consumes one hci_conn reference and the sco_conn owns it for its lifetime. sco_connect() hands over the reference returned by hci_connect_sco() and no longer drops it on the error paths; sco_connect_cfm(), which is not given a reference, takes one with hci_conn_hold() before handing it to sco_conn_add() (and drops it again if the allocation fails); and the explicit hci_conn_hold() in sco_conn_ready() is removed. Every reference then has a single, clear owner.
References
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/8fe627192fa5da7157f9a48608f13c04b6373e43
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/a33bc07b4730b6cd5681ac77d18ae0de3e739690
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/abd93c85c8667add738ee82aeab95dd9fc8265a2
Impacted products
Vendor Product Version
To clipboard 

{
  "affected": [
    {
      "affectedData": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "net/bluetooth/sco.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "lessThan": "a33bc07b4730b6cd5681ac77d18ae0de3e739690",
              "status": "affected",
              "version": "e6720779ae612a14ac4ba7fe4fd5b27d900d932c",
              "versionType": "git"
            },
            {
              "lessThan": "8fe627192fa5da7157f9a48608f13c04b6373e43",
              "status": "affected",
              "version": "e6720779ae612a14ac4ba7fe4fd5b27d900d932c",
              "versionType": "git"
            },
            {
              "lessThan": "abd93c85c8667add738ee82aeab95dd9fc8265a2",
              "status": "affected",
              "version": "e6720779ae612a14ac4ba7fe4fd5b27d900d932c",
              "versionType": "git"
            }
          ]
        },
        {
          "defaultStatus": "affected",
          "product": "Linux",
          "programFiles": [
            "net/bluetooth/sco.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "6.13"
            },
            {
              "lessThan": "6.13",
              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.18.*",
              "status": "unaffected",
              "version": "6.18.44",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "7.1.*",
              "status": "unaffected",
              "version": "7.1.8",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "7.2",
              "versionType": "original_commit_for_fix"
            }
          ]
        }
      ],
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    }
  ],
  "cveTags": [],
  "descriptions": [
    {
      "lang": "en",
      "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nBluetooth: SCO: give the socket its own sco_conn reference\n\nsco_conn_del() drops a reference it does not own. It takes one transient\nreference via sco_conn_hold_unless_zero() and releases it with the\nsco_conn_put() that follows sco_sock_hold(); the additional put in the\n!sk branch releases a second one:\n\n    conn = sco_conn_hold_unless_zero(conn);\n    ...\n    sk = sco_sock_hold(conn);\n    sco_conn_unlock(conn);\n    sco_conn_put(conn);\n\n    if (!sk) {\n            sco_conn_put(conn);\n            return;\n    }\n\nWhen close() races the controller\u0027s Disconnection Complete, sco_chan_del()\nclears conn-\u003esk and drops the socket\u0027s reference while sco_conn_del() is\nrunning. sco_conn_del() then sees sk == NULL, its own put drops the count\nto zero and frees the conn, and the second put writes to the freed kref:\n\n    BUG: KASAN: slab-use-after-free in sco_conn_put.part.0+0x1a/0x190\n    Write of size 4 at addr ffff8881099dec74 by task kworker/u17:3/413\n    Workqueue: hci1 hci_rx_work\n    Call Trace:\n     sco_conn_put.part.0+0x1a/0x190\n     hci_disconn_complete_evt+0x1ee/0x3e0\n     hci_event_packet+0x54a/0x650\n     hci_rx_work+0x321/0x3d0\n    Allocated by task 413:\n     sco_conn_add+0x72/0x1a0\n     sco_connect_cfm+0x88/0x670\n    Freed by task 413:\n     sco_conn_del.isra.0+0x3f/0xf0\n     hci_disconn_complete_evt+0x1ee/0x3e0\n    refcount_t: underflow; use-after-free.\n\nThe root cause is that the socket stores the connection without holding a\nreference of its own. __sco_chan_add() does:\n\n    sco_pi(sk)-\u003econn = conn;\n\nso the socket borrows whatever reference its caller happened to hold, and\nthe callers paper over that with ad-hoc holds and puts. Give the socket a\ncounted reference instead: __sco_chan_add() takes one and it is released\ntogether with the channel (sco_chan_del()) and in sco_sock_destruct().\nWith the socket holding its own reference, sco_conn_del() no longer needs\nthe extra put and the redundant hold in sco_conn_ready() goes away.\n\nMaking the socket own its reference means the connection is now actually\nfreed on the error paths of sco_connect() where it used to leak, which in\nturn runs sco_conn_free() and its hci_conn_drop(conn-\u003ehcon). To keep the\nhci_conn accounting balanced, make that ownership explicit as well:\nsco_conn_add() consumes one hci_conn reference and the sco_conn owns it for\nits lifetime. sco_connect() hands over the reference returned by\nhci_connect_sco() and no longer drops it on the error paths;\nsco_connect_cfm(), which is not given a reference, takes one with\nhci_conn_hold() before handing it to sco_conn_add() (and drops it again if\nthe allocation fails); and the explicit hci_conn_hold() in sco_conn_ready()\nis removed. Every reference then has a single, clear owner."
    }
  ],
  "id": "CVE-2026-80683",
  "lastModified": "2026-10-16T20:18:06.297",
  "metrics": {
    "cvssMetricV31": [
      {
        "cvssData": {
          "attackComplexity": "LOW",
          "attackVector": "ADJACENT_NETWORK",
          "availabilityImpact": "HIGH",
          "baseScore": 8.8,
          "baseSeverity": "HIGH",
          "confidentialityImpact": "HIGH",
          "integrityImpact": "HIGH",
          "privilegesRequired": "NONE",
          "scope": "UNCHANGED",
          "userInteraction": "NONE",
          "vectorString": "CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H",
          "version": "3.1"
        },
        "exploitabilityScore": 2.8,
        "impactScore": 5.9,
        "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "type": "Secondary"
      }
    ],
    "ssvcV203": [
      {
        "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
        "ssvcData": {
          "id": "CVE-2026-80683",
          "options": [
            {
              "exploitation": "none"
            },
            {
              "automatable": "no"
            },
            {
              "technicalImpact": "total"
            }
          ],
          "role": "CISA Coordinator",
          "timestamp": "2026-10-16T19:19:53.842709Z",
          "version": "2.0.3"
        }
      }
    ]
  },
  "published": "2026-08-28T08:16:53.737",
  "references": [
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/8fe627192fa5da7157f9a48608f13c04b6373e43"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/a33bc07b4730b6cd5681ac77d18ae0de3e739690"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/abd93c85c8667add738ee82aeab95dd9fc8265a2"
    }
  ],
  "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
  "vulnStatus": "Received"
}



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