CVE-2026-90092 (GCVE-0-2026-90092)
Vulnerability from cvelistv5
Published
2026-09-17 16:06
Modified
2026-10-19 08:57
Severity ?
8.0 (High) - CVSS:3.1/AV:A/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Summary
In the Linux kernel, the following vulnerability has been resolved: Bluetooth: L2CAP: reject accept queue add unless BT_LISTEN New sk should not be added to parent socket accept queue after last l2cap_sock_cleanup_listen() has run in l2cap_sock_teardown_cb() and state set to BT_CLOSED, as that can result to UAF on dereferencing the dangling parent reference. l2cap_sock_new_connection_cb() may race with parent l2cap_chan teardown, due to chan->state accessed without consistent locking: [Task 1] [Task 2] l2cap_sock_release(parent) l2cap_connect l2cap_sock_shutdown pchan = l2cap_global_chan_by_psm l2cap_chan_lock(pchan) l2cap_chan_close l2cap_sock_teardown_cb pchan->state = BT_CLOSED l2cap_chan_unlock(pchan) ------> l2cap_chan_lock(pchan) l2cap_new_connection l2cap_sock_new_connection_cb l2cap_chan_lock(pchan) <-------- l2cap_chan_unlock(pchan) l2cap_sock_kill(parent) /* bt_sk(sk)->parent dangling */ Fix by adding check for sk_state == BT_LISTEN after acquiring sk lock in l2cap_sock_new_connection_cb(). Add lock_sock() around sk_state writes where missing, to avoid data races. Although the data races on pchan->state should be fixed too, this defensive sk_state check probably makes sense in any case.
References
Impacted products
Vendor Product Version
Linux Linux Version: 0c17c8832562b2aac288e89cefd0f46074f54bcb
Version: 5105f3e6b2df619c635b5f6a49fac131a36c7952
Version: c88c185ae0a1067823661b220aeea613df2c127b
Version: 1810e42ff6716f320c7269d5850eca48b07b7427
Version: 2ff1a41a912de8517b4482e946dd951b7d80edbf
Version: 2ff1a41a912de8517b4482e946dd951b7d80edbf
Version: 1b1c0da227bf63479bac9982fc8d12df9aaea0fb
Version: 85426e97dc72f2088ba6d27e74cd58c3fbd43e31
Version: a2dcf1a61d056aef15b63c6eae9441344d624389
Version: 6.1.175   ≤
Version: 6.6.140   ≤
Version: 6.12.88   ≤
Version: 6.18.30   ≤
Version: 5.10.258   ≤
Version: 5.15.209   ≤
Version: 7.0.7   ≤
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{
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      "descriptions": [
        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nBluetooth: L2CAP: reject accept queue add unless BT_LISTEN\n\nNew sk should not be added to parent socket accept queue after last\nl2cap_sock_cleanup_listen() has run in l2cap_sock_teardown_cb() and\nstate set to BT_CLOSED, as that can result to UAF on dereferencing the\ndangling parent reference.\n\nl2cap_sock_new_connection_cb() may race with parent l2cap_chan teardown,\ndue to chan-\u003estate accessed without consistent locking:\n\n  [Task 1]                           [Task 2]\n  l2cap_sock_release(parent)         l2cap_connect\n    l2cap_sock_shutdown                pchan = l2cap_global_chan_by_psm\n      l2cap_chan_lock(pchan)\n      l2cap_chan_close\n        l2cap_sock_teardown_cb\n          pchan-\u003estate = BT_CLOSED\n      l2cap_chan_unlock(pchan) ------\u003e l2cap_chan_lock(pchan)\n                                       l2cap_new_connection\n                                         l2cap_sock_new_connection_cb\n      l2cap_chan_lock(pchan) \u003c-------- l2cap_chan_unlock(pchan)\n      l2cap_sock_kill(parent)          /* bt_sk(sk)-\u003eparent dangling */\n\nFix by adding check for sk_state == BT_LISTEN after acquiring sk lock in\nl2cap_sock_new_connection_cb().  Add lock_sock() around sk_state writes\nwhere missing, to avoid data races.\n\nAlthough the data races on pchan-\u003estate should be fixed too, this\ndefensive sk_state check probably makes sense in any case."
        }
      ],
      "metrics": [
        {
          "cvssV3_1": {
            "baseScore": 8,
            "baseSeverity": "HIGH",
            "vectorString": "CVSS:3.1/AV:A/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
            "version": "3.1"
          },
          "scenarios": [
            {
              "lang": "en",
              "value": "AV:A - The UAF is reached when a remote peer\u0027s L2CAP Connection Request (L2CAP_CONN_REQ, L2CAP_LE_CONN_REQ, or L2CAP_ECRED_CONN_REQ) is delivered via hci_acldata_packet() \u2192 l2cap_recv_acldata() \u2192 l2cap_recv_frame() into l2cap_connect()/l2cap_le_connect_req(), which calls l2cap_new_connection() \u2192 l2cap_sock_new_connection_cb(). Bluetooth radio range is adjacent.\nAC:L - The race is between the attacker\u0027s close() of their listening socket (l2cap_sock_release() \u2192 l2cap_sock_teardown_cb() setting BT_CLOSED, then l2cap_sock_kill()) and an in-flight L2CAP_CONN_REQ that already passed l2cap_global_chan_by_psm(BT_LISTEN) and is waiting on the chan lock. The attacker owns both sides and can retry.\nPR:L - Triggering the parent-free half requires owning the listener: l2cap_sock_create() has no capability check for SOCK_SEQPACKET/SOCK_STREAM, and l2cap_validate_le_psm()/l2cap_validate_bredr_psm() allow dynamic PSMs (\u22650x0080 LE, \u22650x1001 BR/EDR) without CAP_NET_BIND_SERVICE. smp_sufficient_security() returns true at default BT_SECURITY_LOW, so the LE connect side needs no pairing.\nUI:N - The attacker close()s their own L2CAP listen fd and sends L2CAP Connection Requests from a radio they control; no victim pairing prompt, mount, or other user action is required to reach l2cap_sock_new_connection_cb() or the later l2cap_sock_ready_cb() dereference.\nS:U - The use-after-free corrupts the listening kernel struct sock in kmalloc-2k and stays within the kernel\u0027s own security authority; it is not a VM, IOMMU, or sandbox escape.\nC:H - syzbot KASAN reports a slab-use-after-free Read in l2cap_sock_ready_cb() of the parent sock already freed by l2cap_sock_release()\u2192__sk_destruct(). The child\u0027s dangling bt_sk(sk)-\u003eparent is then used to load parent-\u003esk_data_ready from the freed kmalloc-2k object, so spraying that cache discloses kernel memory.\nI:H - l2cap_sock_ready_cb() calls parent-\u003esk_data_ready(parent) on the freed sock, hijacking a function pointer, and l2cap_sock_teardown_cb() may still run bt_accept_unlink() which list_del_init()s and writes sk_ack_backlog on that same freed parent, giving a write/CFI primitive.\nA:H - The same dangling-parent load in l2cap_sock_ready_cb() is a confirmed slab-use-after-free (syzbot KASAN splat from l2cap_info_timeout()\u2192l2cap_chan_ready()) that oopses or panics the kernel even without a completed exploit."
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-10-19T08:57:50.446Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "references": [
        {
          "url": "https://git.kernel.org/stable/c/bf61a65c6093970e3b50031c4b79ebf3bd411eba"
        },
        {
          "url": "https://git.kernel.org/stable/c/491e4c60017969b053888029998d2a61f298986a"
        },
        {
          "url": "https://git.kernel.org/stable/c/2a3a27aaf19bf069720e024ce6fde54e6bf80df9"
        },
        {
          "url": "https://git.kernel.org/stable/c/87276dc15b559d32757a43b4415c8445fbae06c4"
        },
        {
          "url": "https://git.kernel.org/stable/c/c47339e169bf4a0a4cfabb91351471f67744c2bc"
        },
        {
          "url": "https://git.kernel.org/stable/c/d4bfa78fd67929b62b02013c107973e0c5b7aa9a"
        }
      ],
      "title": "Bluetooth: L2CAP: reject accept queue add unless BT_LISTEN",
      "x_generator": {
        "engine": "bippy-1.2.0"
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
    "assignerShortName": "Linux",
    "cveId": "CVE-2026-90092",
    "datePublished": "2026-09-17T16:06:06.197Z",
    "dateReserved": "2026-09-11T19:38:34.786Z",
    "dateUpdated": "2026-10-19T08:57:50.446Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}


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