CVE-2026-93209 (GCVE-0-2026-93209)
Vulnerability from cvelistv5
Published
2026-09-24 15:10
Modified
2026-10-19 09:07
Severity ?
Summary
In the Linux kernel, the following vulnerability has been resolved: Bluetooth: hci_core: use skb_get() instead of skb_clone() for req_skb BT enable fails intermittently with -ETIMEDOUT (-110). The kernel log shows the HCI Read Local Version command was sent and the firmware replied with status 0x00 (logged by hci_req_cmd_complete() BT_DBG), but the waiter in __hci_cmd_sync_sk() never woke up and timed out after 10 s: bluetooth hci0: Opcode 0xfc00 // __hci_cmd_sync_sk bluetooth hci0: opcode 0xfc00 plen 1 // hci_cmd_sync_add bluetooth hci0: skb len 4 // hci_cmd_sync_alloc bluetooth hci0: length 1 // hci_req_sync_run Bluetooth: hci0 cmd_cnt 1 cmd queued 1 // hci_cmd_work Bluetooth: hci0 type 1 len 4 // hci_send_frame Bluetooth: opcode 0xfc00 status 0x00 // hci_req_cmd_complete <-- req_skb NULL: req_complete_skb not set, hci_cmd_sync_complete() never called, req_status stays HCI_REQ_PEND --> <-- 10 s later: wait_event_interruptible_timeout expires --> bluetooth hci0: end: err -110 // __hci_cmd_sync_sk The root cause is that hci_send_cmd_sync() clones the sent command into hdev->req_skb so that hci_req_cmd_complete() can locate the registered completion callback. Under memory pressure this skb_clone() fails, leaving hdev->req_skb NULL. The firmware reply is received and processed, but hci_req_cmd_complete() finds NULL req_skb, so hci_cmd_sync_complete() is never called, req_status stays HCI_REQ_PEND, and the waiter times out with -ETIMEDOUT. req_skb is only used to read bt_cb(skb)->hci callbacks and opcode -- it is never modified. Replace skb_clone() with skb_get(), which simply increments the reference count of hdev->sent_cmd without allocating new memory and therefore cannot fail. This issue was first observed as a use-after-free in ttyport_close() when ttyport_open() failed, which was investigated in an earlier patch series [1]. That investigation led to the discovery of the true root cause described above. [1] https://lore.kernel.org/all/20250430111617.1151390-1-quic_cxin@quicinc.com/
References
Impacted products
Vendor Product Version
Linux Linux Version: da77c1d39bc527b31890bfa0405763c82828defb
Version: 2af7aa6685e22d0dc546b0d27e5f16d3afe211fa
Version: 2615fd9a7c2507eb3be3fbe49dcec88a2f56454a
Version: 2615fd9a7c2507eb3be3fbe49dcec88a2f56454a
Version: 2615fd9a7c2507eb3be3fbe49dcec88a2f56454a
Version: 2615fd9a7c2507eb3be3fbe49dcec88a2f56454a
Version: 4ff121be63b761950610f422437aaaef8e075c40
Version: 18a4c59af609994552c8b39c5438304e070e55c7
Version: 6.1.83   ≤
Version: 6.6.23   ≤
Version: 6.7.11   ≤
Version: 6.8.2   ≤
Create a notification for this product.
Show details on NVD website

To clipboard 

{
  "containers": {
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "net/bluetooth/hci_core.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "lessThan": "0337fb092873a4146aa854acb554675b49c8f6b5",
              "status": "affected",
              "version": "da77c1d39bc527b31890bfa0405763c82828defb",
              "versionType": "git"
            },
            {
              "lessThan": "d5eef0747071934a1c080ee617fa4fd3566394c5",
              "status": "affected",
              "version": "2af7aa6685e22d0dc546b0d27e5f16d3afe211fa",
              "versionType": "git"
            },
            {
              "lessThan": "d7723320db4c9cb9ec2b9a36140e6c641dd77814",
              "status": "affected",
              "version": "2615fd9a7c2507eb3be3fbe49dcec88a2f56454a",
              "versionType": "git"
            },
            {
              "lessThan": "d0b28e9655f4b3195210627577f81883dc1d0162",
              "status": "affected",
              "version": "2615fd9a7c2507eb3be3fbe49dcec88a2f56454a",
              "versionType": "git"
            },
            {
              "lessThan": "26f66d5b8a5663af498f7ccc94fc79fb47a2191f",
              "status": "affected",
              "version": "2615fd9a7c2507eb3be3fbe49dcec88a2f56454a",
              "versionType": "git"
            },
            {
              "lessThan": "f5afdff569a09d1cb8cf19826199d024725576cb",
              "status": "affected",
              "version": "2615fd9a7c2507eb3be3fbe49dcec88a2f56454a",
              "versionType": "git"
            },
            {
              "status": "affected",
              "version": "4ff121be63b761950610f422437aaaef8e075c40",
              "versionType": "git"
            },
            {
              "status": "affected",
              "version": "18a4c59af609994552c8b39c5438304e070e55c7",
              "versionType": "git"
            },
            {
              "lessThan": "6.1.118",
              "status": "affected",
              "version": "6.1.83",
              "versionType": "semver"
            },
            {
              "lessThan": "6.6.157",
              "status": "affected",
              "version": "6.6.23",
              "versionType": "semver"
            },
            {
              "lessThan": "6.8",
              "status": "affected",
              "version": "6.7.11",
              "versionType": "semver"
            },
            {
              "lessThan": "6.9",
              "status": "affected",
              "version": "6.8.2",
              "versionType": "semver"
            }
          ]
        },
        {
          "defaultStatus": "affected",
          "product": "Linux",
          "programFiles": [
            "net/bluetooth/hci_core.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "6.9"
            },
            {
              "lessThan": "6.9",
              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.1.*",
              "status": "unaffected",
              "version": "6.1.118",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.6.*",
              "status": "unaffected",
              "version": "6.6.157",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.12.*",
              "status": "unaffected",
              "version": "6.12.109",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.18.*",
              "status": "unaffected",
              "version": "6.18.50",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "7.2.*",
              "status": "unaffected",
              "version": "7.2.4",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "7.3",
              "versionType": "original_commit_for_fix"
            }
          ]
        }
      ],
      "cpeApplicability": [
        {
          "nodes": [
            {
              "cpeMatch": [
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.1.118",
                  "versionStartIncluding": "6.1.83",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.6.157",
                  "versionStartIncluding": "6.6.23",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.12.109",
                  "versionStartIncluding": "6.9",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.18.50",
                  "versionStartIncluding": "6.9",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "7.2.4",
                  "versionStartIncluding": "6.9",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "7.3",
                  "versionStartIncluding": "6.9",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionStartIncluding": "6.7.11",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionStartIncluding": "6.8.2",
                  "vulnerable": true
                }
              ],
              "negate": false,
              "operator": "OR"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nBluetooth: hci_core: use skb_get() instead of skb_clone() for req_skb\n\nBT enable fails intermittently with -ETIMEDOUT (-110).  The kernel log\nshows the HCI Read Local Version command was sent and the firmware\nreplied with status 0x00 (logged by hci_req_cmd_complete() BT_DBG),\nbut the waiter in __hci_cmd_sync_sk() never woke up and timed out\nafter 10 s:\n\n  bluetooth hci0: Opcode 0xfc00              // __hci_cmd_sync_sk\n  bluetooth hci0: opcode 0xfc00 plen 1       // hci_cmd_sync_add\n  bluetooth hci0: skb len 4                  // hci_cmd_sync_alloc\n  bluetooth hci0: length 1                   // hci_req_sync_run\n  Bluetooth: hci0 cmd_cnt 1 cmd queued 1     // hci_cmd_work\n  Bluetooth: hci0 type 1 len 4               // hci_send_frame\n  Bluetooth: opcode 0xfc00 status 0x00       // hci_req_cmd_complete\n  \u003c-- req_skb NULL: req_complete_skb not set,\n      hci_cmd_sync_complete() never called,\n      req_status stays HCI_REQ_PEND            --\u003e\n  \u003c-- 10 s later: wait_event_interruptible_timeout expires --\u003e\n  bluetooth hci0: end: err -110              // __hci_cmd_sync_sk\n\nThe root cause is that hci_send_cmd_sync() clones the sent command\ninto hdev-\u003ereq_skb so that hci_req_cmd_complete() can locate the\nregistered completion callback.  Under memory pressure this\nskb_clone() fails, leaving hdev-\u003ereq_skb NULL.  The firmware reply\nis received and processed, but hci_req_cmd_complete() finds NULL\nreq_skb, so hci_cmd_sync_complete() is never called, req_status\nstays HCI_REQ_PEND, and the waiter times out with -ETIMEDOUT.\n\nreq_skb is only used to read bt_cb(skb)-\u003ehci callbacks and opcode --\nit is never modified.  Replace skb_clone() with skb_get(), which\nsimply increments the reference count of hdev-\u003esent_cmd without\nallocating new memory and therefore cannot fail.\n\nThis issue was first observed as a use-after-free in ttyport_close()\nwhen ttyport_open() failed, which was investigated in an earlier\npatch series [1].  That investigation led to the discovery of the\ntrue root cause described above.\n\n[1] https://lore.kernel.org/all/20250430111617.1151390-1-quic_cxin@quicinc.com/"
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-10-19T09:07:21.427Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "references": [
        {
          "url": "https://git.kernel.org/stable/c/0337fb092873a4146aa854acb554675b49c8f6b5"
        },
        {
          "url": "https://git.kernel.org/stable/c/d5eef0747071934a1c080ee617fa4fd3566394c5"
        },
        {
          "url": "https://git.kernel.org/stable/c/d7723320db4c9cb9ec2b9a36140e6c641dd77814"
        },
        {
          "url": "https://git.kernel.org/stable/c/d0b28e9655f4b3195210627577f81883dc1d0162"
        },
        {
          "url": "https://git.kernel.org/stable/c/26f66d5b8a5663af498f7ccc94fc79fb47a2191f"
        },
        {
          "url": "https://git.kernel.org/stable/c/f5afdff569a09d1cb8cf19826199d024725576cb"
        }
      ],
      "title": "Bluetooth: hci_core: use skb_get() instead of skb_clone() for req_skb",
      "x_generator": {
        "engine": "bippy-1.2.0"
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
    "assignerShortName": "Linux",
    "cveId": "CVE-2026-93209",
    "datePublished": "2026-09-24T15:10:32.762Z",
    "dateReserved": "2026-09-17T16:02:15.093Z",
    "dateUpdated": "2026-10-19T09:07:21.427Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}


Log in or create an account to share your comment.




Tags
Taxonomy of the tags.




Sightings

Author Source Type Date

Nomenclature

  • Seen: The vulnerability was mentioned, discussed, or seen somewhere by the user.
  • Confirmed: The vulnerability is confirmed from an analyst perspective.
  • Published Proof of Concept: A public proof of concept is available for this vulnerability.
  • Exploited: This vulnerability was exploited and seen by the user reporting the sighting.
  • Patched: This vulnerability was successfully patched by the user reporting the sighting.
  • Not exploited: This vulnerability was not exploited or seen by the user reporting the sighting.
  • Not confirmed: The user expresses doubt about the veracity of the vulnerability.
  • Not patched: This vulnerability was not successfully patched by the user reporting the sighting.