CVE-2026-90093 (GCVE-0-2026-90093)
Vulnerability from cvelistv5
Published
2026-09-17 16:06
Modified
2026-10-30 12:34
Severity ?
7.8 (High) - CVSS:3.1/AV:L/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: access chan->conn safely in get/setsockopt Since commit b66774b48dd9 ("Bluetooth: L2CAP: Fix UAF in channel timeout by holding conn ref") l2cap_chan::conn has held reference and remains non-NULL also after the corresponding hci_conn is deleted. In this state accessing various fields eg. hci_conn::hdev is invalid, which leads to KASAN crash in l2cap_sock_setsockopt() access of conn->hcon->hdev. Check l2cap_chan::conn.hcon corresponds to an alive hci_conn before trying to use it in l2cap_sock.c. Hold l2cap_chan_lock() in getsockopt/setsockopt to ensure it stays alive, and to avoid data races in l2cap_chan fields.
References
Impacted products
Vendor Product Version
Linux Linux Version: 8f90405a4a6f1f1880dc07996b47bf57c712bd8a
Version: 32d783cafb46ff3ca58e6f9fd62c9c5f35eaf26b
Version: 8922c7940bae9ce4b1736dddb6362370793835c2
Version: 91047a4396a8b1857a6f712a90cf33ec0012b189
Version: 0b0e2bf39cf99e458d991b9df253727e036a7d7d
Version: d3b739db5dc6f688a60d56da872fabaf65246032
Version: b66774b48dd98f07254951f74ea6f513efe7ff8b
Version: b66774b48dd98f07254951f74ea6f513efe7ff8b
Version: 50c38d9f42a529691e4e67ea9cedf4f0bfc8d277
Version: 5.10.265   ≤
Version: 5.15.216   ≤
Version: 6.1.183   ≤
Version: 6.6.145   ≤
Version: 6.12.97   ≤
Version: 6.18.39   ≤
Version: 7.1.4   ≤
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{
  "containers": {
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          "product": "Linux",
          "programFiles": [
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          ],
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              "versionType": "original_commit_for_fix"
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      "cpeApplicability": [
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                  "vulnerable": true
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      "descriptions": [
        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nBluetooth: L2CAP: access chan-\u003econn safely in get/setsockopt\n\nSince commit b66774b48dd9 (\"Bluetooth: L2CAP: Fix UAF in channel timeout by holding conn ref\")\nl2cap_chan::conn has held reference and remains non-NULL also after the\ncorresponding hci_conn is deleted.  In this state accessing various\nfields eg. hci_conn::hdev is invalid, which leads to KASAN crash in\nl2cap_sock_setsockopt() access of conn-\u003ehcon-\u003ehdev.\n\nCheck l2cap_chan::conn.hcon corresponds to an alive hci_conn before\ntrying to use it in l2cap_sock.c.  Hold l2cap_chan_lock() in\ngetsockopt/setsockopt to ensure it stays alive, and to avoid data races\nin l2cap_chan fields."
        }
      ],
      "metrics": [
        {
          "cvssV3_1": {
            "baseScore": 7.8,
            "baseSeverity": "HIGH",
            "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
            "version": "3.1"
          },
          "scenarios": [
            {
              "lang": "en",
              "value": "AV:L - The UAF is reached from __sys_setsockopt/__sys_getsockopt_iter into l2cap_sock_setsockopt()/l2cap_sock_getsockopt(), which dereference chan-\u003econn-\u003ehcon-\u003ehdev after the HCI device is already gone; the trigger is the local BT_FLUSHABLE/BT_SECURITY/BT_PHY sockopt, not a received L2CAP or HCI PDU. Syzbot frees that hdev via vhci_release()-\u003ehci_unregister_dev(), which an in-range peer cannot invoke.\nAC:L - After b66774b48dd9, l2cap_chan_del() sets FLAG_DEL but leaves chan-\u003econn non-NULL, so a later setsockopt(SOL_BLUETOOTH, BT_FLUSHABLE, BT_FLUSHABLE_OFF) deterministically hits lmp_no_flush_capable(conn-\u003ehcon-\u003ehdev) on the deleted hci_conn. The attacker opens the L2CAP socket, tears down the controller (close of /dev/vhci), then issues the sockopt; no un-controllable race or rare config is required.\nPR:L - l2cap_sock_create() requires capable(CAP_NET_RAW) only for SOCK_RAW; SOCK_SEQPACKET/STREAM/DGRAM L2CAP sockets used here have no capability gate, and vhci_open() likewise has no capable() check. An unprivileged init_net user who can open /dev/vhci (or an equivalent HCI node) can create the socket, unregister the controller, and call setsockopt without real root.\nUI:N - The attacker owns both the AF_BLUETOOTH/BTPROTO_L2CAP fd and the teardown fd: they connect, close /dev/vhci so hci_conn_hash_flush()-\u003el2cap_conn_del() runs, then call setsockopt on their still-open socket. No other user must pair, mount, or click anything.\nS:U - l2cap_sock_setsockopt() is using a dangling hci_dev through l2cap_conn-\u003ehcon after hci_release_dev(); the resulting slab UAF stays inside the host kernel Bluetooth stack and does not cross a VM, IOMMU, or sandbox authority.\nC:H - KASAN reports a use-after-free/OOB read in l2cap_sock_setsockopt() of conn-\u003ehcon-\u003ehdev (lmp_no_flush_capable() reads hdev-\u003efeatures[0][6]; getsockopt BT_SECURITY/BT_PHY and L2CAP_CONNINFO also read hcon fields). The freed hci_dev slab was reused as skbuff_small_head, so spraying that object yields a kernel-memory read primitive through the dangling hdev pointer.\nI:H - The same dangling conn-\u003ehcon remains usable from setsockopt after FLAG_DEL: BT_SECURITY on an ATT socket calls smp_conn_security(conn-\u003ehcon) which touches hcon-\u003ehdev flags and hcon-\u003epending_sec_level, and BT_PHY calls hci_conn_set_phy() on that hcon. A sprayed hci_dev in place of the freed object supplies function pointers (send/reset/workqueues) for write and control-flow hijack.\nA:H - Syzbot crashed in l2cap_sock_setsockopt+0x22c3 (net/bluetooth/l2cap_sock.c:1003) with both KASAN slab-out-of-bounds and use-after-free reads of the released hci_dev after vhci_release()-\u003ehci_release_dev(). Any such UAF dereference oopses or panics the kernel and can be repeated by open/connect/close/setsockopt."
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-10-30T12:34:05.630Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "references": [
        {
          "url": "https://git.kernel.org/stable/c/c66cd500ba1a58b3798c468fcc774ed2c8c2ec7d"
        },
        {
          "url": "https://git.kernel.org/stable/c/737b80c97aef10404a9beed7c0ed45fcd5fc5931"
        },
        {
          "url": "https://git.kernel.org/stable/c/0d7b7b31ea092e17d757bd24e2e9028ba5e3a4ca"
        },
        {
          "url": "https://git.kernel.org/stable/c/19e154d794eb4d33d99ca4a087b1cea9d5e65786"
        },
        {
          "url": "https://git.kernel.org/stable/c/3af72bf8f73c519ee562e6963d5ff8e678924f93"
        },
        {
          "url": "https://git.kernel.org/stable/c/8460dc49c9756a1e9288218060b4d41e1b704905"
        },
        {
          "url": "https://git.kernel.org/stable/c/f49321c85785178214fd67f2e9b4b73d6363783b"
        },
        {
          "url": "https://git.kernel.org/stable/c/ca2c4c26498643f421d35ffe258fafbd3ed461c3"
        }
      ],
      "title": "Bluetooth: L2CAP: access chan-\u003econn safely in get/setsockopt",
      "x_generator": {
        "engine": "bippy-1.2.0"
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
    "assignerShortName": "Linux",
    "cveId": "CVE-2026-90093",
    "datePublished": "2026-09-17T16:06:06.843Z",
    "dateReserved": "2026-09-11T19:38:34.786Z",
    "dateUpdated": "2026-10-30T12:34:05.630Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}


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