CVE-2026-89774 (GCVE-0-2026-89774)
Vulnerability from cvelistv5
Published
2026-09-16 08:24
Modified
2026-09-16 14:38
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: hold sk properly in sco_conn_ready sk deref in sco_conn_ready must be done either under conn->lock, or holding a refcount, to avoid concurrent close. conn->sk and parent sk is currently accessed without either, and without checking parent->sk_state: [Task 1] [Task 2] sco_sock_release sco_conn_ready sk = conn->sk lock_sock(sk) conn->sk = NULL lock_sock(sk) release_sock(sk) sco_sock_kill(sk) UAF on sk deref and similarly for access to sco_get_sock_listen() return value. Fix possible UAF by holding sk refcount in sco_conn_ready() and making sco_get_sock_listen() increase refcount. Also recheck after lock_sock that the socket is still valid. Adjust conn->sk locking so it's protected also by lock_sock() of the associated socket if any.
References
Impacted products
Vendor Product Version
Linux Linux Version: 27c24fda62b601d6f9ca5e992502578c4310876f
Version: 27c24fda62b601d6f9ca5e992502578c4310876f
Version: 27c24fda62b601d6f9ca5e992502578c4310876f
Version: 27c24fda62b601d6f9ca5e992502578c4310876f
Version: 27c24fda62b601d6f9ca5e992502578c4310876f
Version: 27c24fda62b601d6f9ca5e992502578c4310876f
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{
  "containers": {
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "net/bluetooth/sco.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
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            }
          ]
        },
        {
          "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": "5.15"
            },
            {
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              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "5.15.*",
              "status": "unaffected",
              "version": "5.15.212",
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            },
            {
              "lessThanOrEqual": "6.1.*",
              "status": "unaffected",
              "version": "6.1.178",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.6.*",
              "status": "unaffected",
              "version": "6.6.145",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.12.*",
              "status": "unaffected",
              "version": "6.12.97",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.18.*",
              "status": "unaffected",
              "version": "6.18.40",
              "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": "5.15.212",
                  "versionStartIncluding": "5.15",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.1.178",
                  "versionStartIncluding": "5.15",
                  "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: SCO: hold sk properly in sco_conn_ready\n\nsk deref in sco_conn_ready must be done either under conn-\u003elock, or\nholding a refcount, to avoid concurrent close. conn-\u003esk and parent sk is\ncurrently accessed without either, and without checking parent-\u003esk_state:\n\n    [Task 1]            [Task 2]\n                        sco_sock_release\n    sco_conn_ready\n      sk = conn-\u003esk\n                          lock_sock(sk)\n                            conn-\u003esk = NULL\n      lock_sock(sk)\n                          release_sock(sk)\n                          sco_sock_kill(sk)\n       UAF on sk deref\n\nand similarly for access to sco_get_sock_listen() return value.\n\nFix possible UAF by holding sk refcount in sco_conn_ready() and making\nsco_get_sock_listen() increase refcount. Also recheck after lock_sock\nthat the socket is still valid.  Adjust conn-\u003esk locking so it\u0027s\nprotected also by lock_sock() of the associated socket if any."
        }
      ],
      "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 - sco_conn_ready runs from sco_connect_cfm via hci_connect_cfm on HCI Connection Complete, Synchronous Connection Complete, and deferred Connection Request for SCO/eSCO, driven by an in-range Bluetooth peer. Kernel CNA guidance classifies Bluetooth as Adjacent.\nAC:L - This is a use-after-free race between sco_conn_ready and sco_sock_release/sco_sock_kill. An attacker who times HCI SCO completion against socket close (rapid peer establish/teardown or concurrent connect/close) controls both sides and can retry until the window is hit; CONFIG_BT_BREDR defaults to y.\nPR:N - Incoming SCO is accepted when any listen socket exists (typical HFP/audio daemons on phones) with no Linux credentials required of the peer. sco_sock_create has no capability check, and listener close can occur from automatic bluetoothd/PipeWire teardown during connection setup.\nUI:N - No victim action is required at exploit time. OS Bluetooth audio stacks keep SCO listeners and manage sockets during normal headset, hands-free, and automotive operation while peer-initiated SCO/eSCO traffic is processed.\nS:U - The use-after-free corrupts in-kernel Bluetooth socket memory and can enable privilege escalation within the same host kernel security authority. It does not cross a VM, container, or IOMMU boundary.\nC:H - Use-after-free of struct sock after sco_sock_kill lets an attacker reclaim the freed slab object and read kernel memory through subsequent sock operations, which per CNA guidance is High confidentiality impact.\nI:H - sco_conn_ready writes sk-\u003esk_state and makes an indirect call through sk-\u003esk_state_change on the freed sock, a standard kernel heap UAF primitive for arbitrary write and control-flow hijack, scored High per UAF guidance.\nA:H - lock_sock and subsequent sk field access on a freed socket cause a kernel oops or panic. Per CNA guidance any use-after-free is High availability impact even before full exploitation."
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-09-16T14:38:26.042Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "references": [
        {
          "url": "https://git.kernel.org/stable/c/50aae396dc30377bec8e3b181b8346f8fd38f7d8"
        },
        {
          "url": "https://git.kernel.org/stable/c/6e3840578aaad1a296aab1eaaa89ea3b7d5cbae1"
        },
        {
          "url": "https://git.kernel.org/stable/c/d141d9b769bcd1b747898528c5023270cda040f2"
        },
        {
          "url": "https://git.kernel.org/stable/c/73cb063f5ec6ca51eb1e246c6d332563002ac277"
        },
        {
          "url": "https://git.kernel.org/stable/c/7199c78c3a3e399a4dc439d845826793880ccedc"
        },
        {
          "url": "https://git.kernel.org/stable/c/4e37f6452d586b95c346a9abdd2fb80b67794f39"
        }
      ],
      "title": "Bluetooth: SCO: hold sk properly in sco_conn_ready",
      "x_generator": {
        "engine": "bippy-1.2.0"
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
    "assignerShortName": "Linux",
    "cveId": "CVE-2026-89774",
    "datePublished": "2026-09-16T08:24:21.248Z",
    "dateReserved": "2026-09-11T19:38:34.765Z",
    "dateUpdated": "2026-09-16T14:38:26.042Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}


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