CVE-2026-68085 (GCVE-0-2026-68085)
Vulnerability from cvelistv5
Published
2026-08-10 11:51
Modified
2026-08-17 04:58
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: hci_uart: clear HCI_UART_SENDING when write_work is canceled HCI_UART_SENDING bit in tx_state means write_work is pending and blocks queueing it again. Currently this bit is not cleared when canceling the work in hci_uart_close(), which blocks future writes when device is reopened later if write_work was pending. Fix by clearing HCI_UART_SENDING when canceling the work. Also make clearing of tx_skb safe by using disable_work_sync + enable_work instead of just cancel_work_sync. hci_uart_flush() purges the proto tx queue so we can cancel the pending write_work there, instead of doing it just in hci_uart_close(). Re-enable and possibly requeue the work after queue flush.
References
Impacted products
Vendor Product Version
Linux Linux Version: 81c7a3c22a0f2808cf4ae0b4908f59763b23606d
Version: 192cb0f1ca706d9a1bc36ae0ad5f666d1e4fd894
Version: c1bb9336ae6b54a5f6a353c4bd4ed9a4307e429b
Version: c1bb9336ae6b54a5f6a353c4bd4ed9a4307e429b
Version: 78aad93e938f013d9272fe0ee168f27883afa95c
Version: e2d19969c8d9198ecc3090bcd5312ecd503a3339
Version: c85cff648a2bc92322912db5f1727ad05afae7b6
Version: 9d20d48be2c4a071fb015eb09bda2cecd25daf34
Version: 7338031946bd06f6dff149e67b60c4cd083bfea8
Version: 6.12.92   ≤
Version: 6.18.34   ≤
Version: 5.10.258   ≤
Version: 5.15.209   ≤
Version: 6.1.175   ≤
Version: 6.6.142   ≤
Version: 7.0.11   ≤
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{
  "containers": {
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "drivers/bluetooth/hci_ldisc.c"
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          "defaultStatus": "affected",
          "product": "Linux",
          "programFiles": [
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          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
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              "versionType": "original_commit_for_fix"
            }
          ]
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      ],
      "cpeApplicability": [
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          "nodes": [
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              "negate": false,
              "operator": "OR"
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          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nBluetooth: hci_uart: clear HCI_UART_SENDING when write_work is canceled\n\nHCI_UART_SENDING bit in tx_state means write_work is pending and blocks\nqueueing it again.  Currently this bit is not cleared when canceling the\nwork in hci_uart_close(), which blocks future writes when device is\nreopened later if write_work was pending.\n\nFix by clearing HCI_UART_SENDING when canceling the work.\n\nAlso make clearing of tx_skb safe by using disable_work_sync +\nenable_work instead of just cancel_work_sync.  hci_uart_flush() purges\nthe proto tx queue so we can cancel the pending write_work there,\ninstead of doing it just in hci_uart_close().  Re-enable and possibly\nrequeue the work after queue flush."
        }
      ],
      "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 flaw is in the Bluetooth HCI UART TX teardown path; an adjacent Bluetooth peer can drive HCI traffic to keep write_work pending while privileged stack management (HCIDEVRESET/close during adapter recovery) executes hci_uart_close/flush.\nAC:L - An attacker controls both sides of the race by generating HCI TX to set HCI_UART_SENDING and concurrently triggering adapter close/reset (e.g., HCIDEVRESET), making the stuck-bit and tx_skb teardown races reliably reachable.\nPR:L - Direct exploitation requires CAP_NET_ADMIN to attach the N_HCI TTY line discipline and issue HCIDEVDOWN/HCIDEVRESET ioctls; this capability is available to unprivileged users inside user namespaces, not only init-namespace root.\nUI:N - No victim interaction is required beyond normal Bluetooth operation; exploitation is achieved through attacker-driven HCI traffic and adapter close/reset timing without the user opening files or confirming prompts.\nS:U - Impact is confined to kernel Bluetooth/UART state on the host (permanent TX failure or kernel crash); it does not cross a VM, container, or IOMMU security boundary to affect a different authority.\nC:H - The vulnerable hci_uart_flush path can race with protocol timers requeueing write_work, causing tx_skb double-free/UAF heap corruption that can expose kernel memory contents, not merely a functional TX stall.\nI:H - Concurrent flush and write_work on tx_skb enables heap corruption primitives typical of double-free/UAF bugs in the kernel slab allocator, which can be leveraged for arbitrary memory writes and code execution.\nA:H - Leaving HCI_UART_SENDING set after cancel permanently blocks all future Bluetooth transmissions after reopen until full teardown, and the tx_skb corruption race can trigger kernel oops/panic."
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-08-17T04:58:33.786Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "references": [
        {
          "url": "https://git.kernel.org/stable/c/d52446b3e735cfdbdc2a58342163803bc2e64249"
        },
        {
          "url": "https://git.kernel.org/stable/c/b9dd39cf1667e378b25a082ca796d495d578c5d3"
        },
        {
          "url": "https://git.kernel.org/stable/c/714d861d35d937f23375a4517569b13917bbbe51"
        },
        {
          "url": "https://git.kernel.org/stable/c/1b0d946d6f08bd39211385bc703a440911b41e46"
        }
      ],
      "title": "Bluetooth: hci_uart: clear HCI_UART_SENDING when write_work is canceled",
      "x_generator": {
        "engine": "bippy-1.2.0"
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
    "assignerShortName": "Linux",
    "cveId": "CVE-2026-68085",
    "datePublished": "2026-08-10T11:51:39.079Z",
    "dateReserved": "2026-07-30T09:28:09.367Z",
    "dateUpdated": "2026-08-17T04:58:33.786Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}


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