CVE-2026-93209

Description

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/

Overview

State: PUBLISHED
Assigner (CNA): Linux
CVSS severity: —
CVSS score: —
CVSS vector: —
Effective score: no score available from CNA, NVD, or AI yet
CWE(s): —
Reserved: 2026-09-17
Published: 2026-09-24 15:10 UTC
Last updated: 2026-09-24 15:10 UTC
Source: https://raw.githubusercontent.com/CVEProject/cvelistV5/main/cves/2026/93xxx/CVE-2026-93209.json

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European Union Vulnerability Database ENISA EUVD

ENISA's official EU repository for curated vulnerability intelligence. Carries a separate identifier (EUVD-YYYY-NNNN) and frequently exposes an earlier-published description + CVSS than NVD does.

EUVD ID: EUVD-2026-85938
Assigner: Linux
Published: Sep 24, 2026, 3:10:32 PM
Updated: Sep 24, 2026, 3:10:32 PM
EUVD base score: 0.0 / 10
EUVD-reported EPSS: 0.0000
Vendors: Linux
Products: Linux (4ff121be63b761950610f422437aaaef8e075c40)

Linux (patch: 6.6.157)

Linux (da77c1d39bc527b31890bfa0405763c82828defb <0337fb092873a4146aa854acb554675b49c8f6b5)

Linux (patch: 7.3-rc1)

Linux (2615fd9a7c2507eb3be3fbe49dcec88a2f56454a <f5afdff569a09d1cb8cf19826199d024725576cb)

Linux (patch: 6.12.109)

Linux (6.9)

Linux (2615fd9a7c2507eb3be3fbe49dcec88a2f56454a <26f66d5b8a5663af498f7ccc94fc79fb47a2191f)

Linux (patch: 6.1.118)

Linux (6.8.2 <6.9)

Linux (2615fd9a7c2507eb3be3fbe49dcec88a2f56454a <d7723320db4c9cb9ec2b9a36140e6c641dd77814)

Linux (patch: 0)

Linux (18a4c59af609994552c8b39c5438304e070e55c7)

Linux (patch: 7.2.4)

Linux (6.7.11 <6.8)

Linux (2af7aa6685e22d0dc546b0d27e5f16d3afe211fa <d5eef0747071934a1c080ee617fa4fd3566394c5)

Linux (6.6.23 <6.6.157)

Linux (2615fd9a7c2507eb3be3fbe49dcec88a2f56454a <d0b28e9655f4b3195210627577f81883dc1d0162)

Linux (6.1.83 <6.1.118)

Linux (patch: 6.18.50)
Aliases: GHSA-vfrj-34f5-pwh8

ENISA description: 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/

EUVD references (6)

Affected products (2)

Vendor	Product	Versions	Platforms
Linux	Linux	`da77c1d39bc527b31890bfa0405763c82828defb` (affected), `2af7aa6685e22d0dc546b0d27e5f16d3afe211fa` (affected), `2615fd9a7c2507eb3be3fbe49dcec88a2f56454a` (affected), `2615fd9a7c2507eb3be3fbe49dcec88a2f56454a` (affected), `2615fd9a7c2507eb3be3fbe49dcec88a2f56454a` (affected), `2615fd9a7c2507eb3be3fbe49dcec88a2f56454a` (affected), `4ff121be63b761950610f422437aaaef8e075c40` (affected), `18a4c59af609994552c8b39c5438304e070e55c7` (affected), `6.1.83` (affected), `6.6.23` (affected), `6.7.11` (affected), `6.8.2` (affected)	—
Linux	Linux	`6.9` (affected), `0` (unaffected), `6.1.118` (unaffected), `6.6.157` (unaffected), `6.12.109` (unaffected), `6.18.50` (unaffected), `7.2.4` (unaffected), `7.3-rc1` (unaffected)	—

Vendor references (6)

References embedded in the original CVE record by the assigning CNA.

Web references (0)

DuckDuckGo results ranked by threat-intel / vendor advisory domains. Generated by the 🔎 Find references (web) button above — same flow as the Remediations search.

No web references attached yet.

Remediations (10)

Security Advisories and Bulletins | Microsoft Learn

web:learn.microsoft.com

Learning path Learn how Microsoft supports secure software development as part of a cybersecurity solution - Training Secure software development means integrating security into each phase of your development lifecycle, from requirements analysis to maintenance. Microsoft provides many services that can help you develop more secure code and deploy a more secure application in the cloud. This ...

2026-09-25 10:45 UTC
Security Update Guide - Microsoft

web:msrc-ppe.microsoft.com

The Microsoft Security Response Center (MSRC) investigates all reports of security vulnerabilities affecting Microsoft products and services, and provides the information here as part of the ongoing effort to help you manage security risks and help keep your systems protected.

2026-09-25 10:45 UTC
Security Update Guide - Microsoft Security Response Center

web:msrc.microsoft.com

Access Microsoft Security Response Center's guide to address vulnerabilities, manage security risks, and keep your systems protected with the latest updates.

2026-09-25 10:45 UTC
Microsoft Office Zero-Day (CVE-2026-21509) - Emergency Patch Issued for ...

web:thehackernews.com

Microsoft released out-of-band patches for an actively exploited Microsoft Office zero-day, CVE - 2026 -21509, a security feature bypass flaw.

2026-09-25 10:45 UTC
September 2026 Patch Tuesday: CISO Executive Summary

web:www.action1.com

This CISO-focused summary highlights the vulnerabilities and critical infrastructure risks that should take priority for remediation following Microsoft's September 2026 Patch Tuesday release.

2026-09-25 10:45 UTC
Critical Patches Issued for Microsoft Products, September 8, 2026

web:www.cisecurity.org

<p>Multiple vulnerabilities have been discovered in Microsoft products, the most severe of which could allow for remote code execution. Successful exploitation of the most severe of these vulnerabilities could result in an attacker gaining the same privileges as the logged-on user. Depending on the privileges associated with the user, an attacker could then install programs; view, change, or ...

2026-09-25 10:45 UTC
CVE: Common Vulnerabilities and Exposures

web:www.cve.org

At cve .org, we provide the authoritative reference method for publicly known information-security vulnerabilities and exposures

2026-09-25 10:45 UTC
Microsoft Technical Security Notifications

web:www.microsoft.com

Microsoft's free Security Update Guide Notifications provide links to security-related software updates and notification of re-released security updates. These notifications are sent via email throughout the month as needed. You can choose the type of updates for which you want to be notified: Major ...

2026-09-25 10:45 UTC
Office zero-day exploited, forces Microsoft OOB patch

web:www.theregister.com

Office zero-day exploited in the wild forces Microsoft OOB patch Another actively abused Office bug, another emergency patch - Office 2016 and 2019 users are left with registry tweaks instead of fixes.

2026-09-25 10:45 UTC
Patch Tuesday September 2026: Security Updates & CVE Analysis

web:zecurit.com

Get the complete breakdown of Microsoft's September 2026 Patch Tuesday. We analyze the latest security updates and all critical CVEs .

2026-09-25 10:45 UTC

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Raw JSON

The full cvelistV5 record. Download as CVE-2026-93209.json.

{
  "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": [
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              "status": "affected",
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            {
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              "versionType": "git"
            },
            {
              "lessThan": "d0b28e9655f4b3195210627577f81883dc1d0162",
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              "versionType": "git"
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            {
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            {
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              "version": "4ff121be63b761950610f422437aaaef8e075c40",
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              "version": "18a4c59af609994552c8b39c5438304e070e55c7",
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              "status": "affected",
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            },
            {
              "lessThan": "6.8",
              "status": "affected",
              "version": "6.7.11",
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            },
            {
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              "version": "6.8.2",
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            }
          ]
        },
        {
          "defaultStatus": "affected",
          "product": "Linux",
          "programFiles": [
            "net/bluetooth/hci_core.c"
          ],
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          "vendor": "Linux",
          "versions": [
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            },
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            {
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              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.6.*",
              "status": "unaffected",
              "version": "6.6.157",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.12.*",
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            {
              "lessThanOrEqual": "6.18.*",
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            {
              "lessThanOrEqual": "7.2.*",
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            },
            {
              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "7.3-rc1",
              "versionType": "original_commit_for_fix"
            }
          ]
        }
      ],
      "cpeApplicability": [
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          "nodes": [
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                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
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                  "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:*:*:*:*:*:*:*:*",
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                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
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                {
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                  "versionEndExcluding": "7.3-rc1",
                  "versionStartIncluding": "6.9",
                  "vulnerable": true
                },
                {
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                  "versionStartIncluding": "6.7.11",
                  "vulnerable": true
                },
                {
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                  "versionStartIncluding": "6.8.2",
                  "vulnerable": true
                }
              ],
              "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_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  <-- req_skb NULL: req_complete_skb not set,\n      hci_cmd_sync_complete() never called,\n      req_status stays HCI_REQ_PEND            -->\n  <-- 10 s later: wait_event_interruptible_timeout expires -->\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->req_skb so that hci_req_cmd_complete() can locate the\nregistered completion callback.  Under memory pressure this\nskb_clone() fails, leaving hdev->req_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)->hci callbacks and opcode --\nit is never modified.  Replace skb_clone() with skb_get(), which\nsimply increments the reference count of hdev->sent_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": "2026-09-24T15:10:32.762Z",
        "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": "2026-09-24T15:10:32.762Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}