GHSA-WVXR-8P4P-PCPQ
Vulnerability from github – Published: 2026-05-01 15:30 – Updated: 2026-05-03 09:33In the Linux kernel, the following vulnerability has been resolved:
Bluetooth: SCO: fix race conditions in sco_sock_connect()
sco_sock_connect() checks sk_state and sk_type without holding the socket lock. Two concurrent connect() syscalls on the same socket can both pass the check and enter sco_connect(), leading to use-after-free.
The buggy scenario involves three participants and was confirmed with additional logging instrumentation:
Thread A (connect): HCI disconnect: Thread B (connect):
sco_sock_connect(sk) sco_sock_connect(sk) sk_state==BT_OPEN sk_state==BT_OPEN (pass, no lock) (pass, no lock) sco_connect(sk): sco_connect(sk): hci_dev_lock hci_dev_lock hci_connect_sco <- blocked -> hcon1 sco_conn_add->conn1 lock_sock(sk) sco_chan_add: conn1->sk = sk sk->conn = conn1 sk_state=BT_CONNECT release_sock hci_dev_unlock hci_dev_lock sco_conn_del: lock_sock(sk) sco_chan_del: sk->conn=NULL conn1->sk=NULL sk_state= BT_CLOSED SOCK_ZAPPED release_sock hci_dev_unlock (unblocked) hci_connect_sco -> hcon2 sco_conn_add -> conn2 lock_sock(sk) sco_chan_add: sk->conn=conn2 sk_state= BT_CONNECT // zombie sk! release_sock hci_dev_unlock
Thread B revives a BT_CLOSED + SOCK_ZAPPED socket back to BT_CONNECT. Subsequent cleanup triggers double sock_put() and use-after-free. Meanwhile conn1 is leaked as it was orphaned when sco_conn_del() cleared the association.
Fix this by: - Moving lock_sock() before the sk_state/sk_type checks in sco_sock_connect() to serialize concurrent connect attempts - Fixing the sk_type != SOCK_SEQPACKET check to actually return the error instead of just assigning it - Adding a state re-check in sco_connect() after lock_sock() to catch state changes during the window between the locks - Adding sco_pi(sk)->conn check in sco_chan_add() to prevent double-attach of a socket to multiple connections - Adding hci_conn_drop() on sco_chan_add failure to prevent HCI connection leaks
{
"affected": [],
"aliases": [
"CVE-2026-43023"
],
"database_specific": {
"cwe_ids": [
"CWE-362"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2026-05-01T15:16:46Z",
"severity": "HIGH"
},
"details": "In the Linux kernel, the following vulnerability has been resolved:\n\nBluetooth: SCO: fix race conditions in sco_sock_connect()\n\nsco_sock_connect() checks sk_state and sk_type without holding\nthe socket lock. Two concurrent connect() syscalls on the same\nsocket can both pass the check and enter sco_connect(), leading\nto use-after-free.\n\nThe buggy scenario involves three participants and was confirmed\nwith additional logging instrumentation:\n\n Thread A (connect): HCI disconnect: Thread B (connect):\n\n sco_sock_connect(sk) sco_sock_connect(sk)\n sk_state==BT_OPEN sk_state==BT_OPEN\n (pass, no lock) (pass, no lock)\n sco_connect(sk): sco_connect(sk):\n hci_dev_lock hci_dev_lock\n hci_connect_sco \u003c- blocked\n -\u003e hcon1\n sco_conn_add-\u003econn1\n lock_sock(sk)\n sco_chan_add:\n conn1-\u003esk = sk\n sk-\u003econn = conn1\n sk_state=BT_CONNECT\n release_sock\n hci_dev_unlock\n hci_dev_lock\n sco_conn_del:\n lock_sock(sk)\n sco_chan_del:\n sk-\u003econn=NULL\n conn1-\u003esk=NULL\n sk_state=\n BT_CLOSED\n SOCK_ZAPPED\n release_sock\n hci_dev_unlock\n (unblocked)\n hci_connect_sco\n -\u003e hcon2\n sco_conn_add\n -\u003e conn2\n lock_sock(sk)\n sco_chan_add:\n sk-\u003econn=conn2\n sk_state=\n BT_CONNECT\n // zombie sk!\n release_sock\n hci_dev_unlock\n\nThread B revives a BT_CLOSED + SOCK_ZAPPED socket back to\nBT_CONNECT. Subsequent cleanup triggers double sock_put() and\nuse-after-free. Meanwhile conn1 is leaked as it was orphaned\nwhen sco_conn_del() cleared the association.\n\nFix this by:\n- Moving lock_sock() before the sk_state/sk_type checks in\n sco_sock_connect() to serialize concurrent connect attempts\n- Fixing the sk_type != SOCK_SEQPACKET check to actually\n return the error instead of just assigning it\n- Adding a state re-check in sco_connect() after lock_sock()\n to catch state changes during the window between the locks\n- Adding sco_pi(sk)-\u003econn check in sco_chan_add() to prevent\n double-attach of a socket to multiple connections\n- Adding hci_conn_drop() on sco_chan_add failure to prevent\n HCI connection leaks",
"id": "GHSA-wvxr-8p4p-pcpq",
"modified": "2026-05-03T09:33:10Z",
"published": "2026-05-01T15:30:36Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2026-43023"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/7e296ffdab5bdab718dff7c14288fdcb9154fa27"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/8a5b0135d4a5d9683203a3d9a12a711ccec5936b"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/98c8d3bfdaa657d8f472dbbebd7ea8cd816d8a8d"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/adb90cd0f9f7a8d438fcb93354040fbafc5ae2a0"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/d002bd11024bd231bcb606877e33951ffb7bed14"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/dabf22269242e2f2bf44c43fcdc2fa763df7f9cc"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
"type": "CVSS_V3"
}
]
}
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