CVE-2026-53357 (GCVE-0-2026-53357)
Vulnerability from cvelistv5
Published
2026-07-02 13:43
Modified
2026-08-05 12:35
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: fix UAF in l2cap_sock_cleanup_listen() vs l2cap_conn_del() bt_accept_dequeue() unlinks a not-yet-accepted child from the parent accept queue and release_sock()s it before returning, so the returned sk has no caller reference and is unlocked. l2cap_sock_cleanup_listen() walks these children on listening-socket close. A concurrent HCI disconnect drives hci_rx_work -> l2cap_conn_del() which runs l2cap_chan_del() + l2cap_sock_kill() and frees the child sk and its l2cap_chan; cleanup_listen() then uses both: BUG: KASAN: slab-use-after-free in l2cap_sock_kill l2cap_sock_kill / l2cap_sock_cleanup_listen / __x64_sys_close Freed by: l2cap_conn_del -> l2cap_sock_close_cb -> l2cap_sock_kill This is distinct from the two fixes already in this area: commit e83f5e24da741 ("Bluetooth: serialize accept_q access") serialises the accept_q list/poll and takes temporary refs inside bt_accept_dequeue(), and CVE-2025-39860 serialises the userspace close()/accept() race by calling cleanup_listen() under lock_sock() in l2cap_sock_release(). Neither covers l2cap_conn_del() running from hci_rx_work, so this UAF still reproduces on current bluetooth/master. Take the reference at the source: bt_accept_dequeue() does sock_hold() while sk is still locked, before release_sock(); callers sock_put(). cleanup_listen() pins the chan with l2cap_chan_hold_unless_zero() under a brief child sk lock (serialising vs l2cap_sock_teardown_cb()), drops it before l2cap_chan_lock(), and skips a duplicate l2cap_sock_kill() on SOCK_DEAD. conn->lock is not taken here: cleanup_listen() runs under the parent sk lock and that would invert conn->lock -> chan->lock -> sk_lock (lockdep). KASAN/SMP: an unprivileged listen/close vs HCI-disconnect race produced 12 use-after-free reports per run before this change; 0, and no lockdep report, over 1600+ raced iterations after it on bluetooth/master.
References
Impacted products
Vendor Product Version
Linux Linux Version: 15f02b91056253e8cdc592888f431da0731337b8
Version: 15f02b91056253e8cdc592888f431da0731337b8
Version: 15f02b91056253e8cdc592888f431da0731337b8
Version: 15f02b91056253e8cdc592888f431da0731337b8
Version: 15f02b91056253e8cdc592888f431da0731337b8
Version: 15f02b91056253e8cdc592888f431da0731337b8
Version: 15f02b91056253e8cdc592888f431da0731337b8
Version: 15f02b91056253e8cdc592888f431da0731337b8
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{
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            "net/bluetooth/af_bluetooth.c",
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            "net/bluetooth/sco.c"
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      "descriptions": [
        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nBluetooth: fix UAF in l2cap_sock_cleanup_listen() vs l2cap_conn_del()\n\nbt_accept_dequeue() unlinks a not-yet-accepted child from the parent\naccept queue and release_sock()s it before returning, so the returned\nsk has no caller reference and is unlocked.\n\nl2cap_sock_cleanup_listen() walks these children on listening-socket\nclose.  A concurrent HCI disconnect drives hci_rx_work -\u003e\nl2cap_conn_del() which runs l2cap_chan_del() + l2cap_sock_kill() and\nfrees the child sk and its l2cap_chan; cleanup_listen() then uses both:\n\n  BUG: KASAN: slab-use-after-free in l2cap_sock_kill\n    l2cap_sock_kill / l2cap_sock_cleanup_listen / __x64_sys_close\n  Freed by: l2cap_conn_del -\u003e l2cap_sock_close_cb -\u003e l2cap_sock_kill\n\nThis is distinct from the two fixes already in this area: commit\ne83f5e24da741 (\"Bluetooth: serialize accept_q access\") serialises the\naccept_q list/poll and takes temporary refs inside bt_accept_dequeue(),\nand CVE-2025-39860 serialises the userspace close()/accept() race by\ncalling cleanup_listen() under lock_sock() in l2cap_sock_release().\nNeither covers l2cap_conn_del() running from hci_rx_work, so this UAF\nstill reproduces on current bluetooth/master.\n\nTake the reference at the source: bt_accept_dequeue() does sock_hold()\nwhile sk is still locked, before release_sock(); callers sock_put().\ncleanup_listen() pins the chan with l2cap_chan_hold_unless_zero() under\na brief child sk lock (serialising vs l2cap_sock_teardown_cb()), drops\nit before l2cap_chan_lock(), and skips a duplicate l2cap_sock_kill() on\nSOCK_DEAD.  conn-\u003elock is not taken here: cleanup_listen() runs under\nthe parent sk lock and that would invert\nconn-\u003elock -\u003e chan-\u003elock -\u003e sk_lock (lockdep).\n\nKASAN/SMP: an unprivileged listen/close vs HCI-disconnect race produced\n12 use-after-free reports per run before this change; 0, and no lockdep\nreport, over 1600+ raced iterations after it on bluetooth/master."
        }
      ],
      "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 race is driven through Bluetooth L2CAP/HCI connection and disconnect handling from a nearby peer, so it is limited to Bluetooth-adjacent reachability rather than routable network access. The local listener/close side is accounted for in PR.\nAC:L - This is a race, but the attacker can reasonably control the listener close timing and the Bluetooth peer disconnect timing. The commit reports reliable unprivileged raced iterations, so no uncontrollable condition is required.\nPR:L - Creating, binding to a dynamic PSM, listening on, and closing non-raw L2CAP sockets does not require capabilities; only raw sockets or reserved PSMs need privileges. A basic unprivileged local user on the target can set up the vulnerable listener.\nUI:N - No victim user action is required once the attacker can run the unprivileged local setup and control the Bluetooth peer. The trigger is socket close racing HCI disconnect processing.\nS:U - The corruption is within the Linux kernel Bluetooth/socket subsystem and impacts the same kernel security authority. It is not a VM escape or cross-scope boundary bypass.\nC:H - The bug is a use-after-free of both the child sock and its l2cap_chan, and freed kernel heap objects can be reclaimed and used for disclosure primitives. Per kernel CVSS guidance, UAF memory corruption supports high confidentiality impact.\nI:H - The stale sock/channel pointers are used after l2cap_conn_del frees them, including through cleanup and kill paths, making heap grooming and control-flow or write-primitive exploitation plausible. Per guidance, UAF memory corruption supports high integrity impact.\nA:H - The observed failure is a KASAN slab-use-after-free in kernel Bluetooth cleanup, which can crash or oops the kernel. Repeated triggering can deny availability."
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-08-05T12:35:06.665Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "references": [
        {
          "url": "https://git.kernel.org/stable/c/751de6ec671fe75ad9cf65a0638d2a06b6a5984d"
        },
        {
          "url": "https://git.kernel.org/stable/c/407217734835d21d4e0105ebf347860dc1806f88"
        },
        {
          "url": "https://git.kernel.org/stable/c/7eebd4c2c86f573af87ff165d08a83432eb0b919"
        },
        {
          "url": "https://git.kernel.org/stable/c/5d86d2f1b4d9a508c441d3e45277ae1a73cfed57"
        },
        {
          "url": "https://git.kernel.org/stable/c/87c543e2f78d0871f271df92dab98901bbd5b6f5"
        },
        {
          "url": "https://git.kernel.org/stable/c/added1213395071470a900cc845a042fb51882a6"
        },
        {
          "url": "https://git.kernel.org/stable/c/a5ca86a6097a8b030ca3226cd300b17ed330f966"
        },
        {
          "url": "https://git.kernel.org/stable/c/ab1513597c6cf17cd1ad2a21e3b045421b48e022"
        }
      ],
      "title": "Bluetooth: fix UAF in l2cap_sock_cleanup_listen() vs l2cap_conn_del()",
      "x_generator": {
        "engine": "bippy-1.2.0"
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
    "assignerShortName": "Linux",
    "cveId": "CVE-2026-53357",
    "datePublished": "2026-07-02T13:43:17.077Z",
    "dateReserved": "2026-06-09T07:44:35.400Z",
    "dateUpdated": "2026-08-05T12:35:06.665Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}


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