CVE-2026-98734 (GCVE-0-2026-98734)

Vulnerability from cvelistv5 – Published: 2026-10-18 15:47 – Updated: 2026-10-21 12:56
VLAI
Title
Bluetooth: hci_core: Serialize SCO and ISO scheduling with teardown
Summary
In the Linux kernel, the following vulnerability has been resolved: Bluetooth: hci_core: Serialize SCO and ISO scheduling with teardown hci_low_sent() selects a connection under RCU but drops the read lock before calculating its quota and returning it to the scheduler. The connection is then used without lifetime protection by hci_sched_iso() and hci_sched_sco(). After the TX worker drops the RCU read lock, hci_abort_conn_sync() on hdev->req_workqueue can remove the connection from the hash, complete synchronize_rcu(), purge its queues and release it. The TX worker on hdev->workqueue can then access the freed connection in hci_quote_sent() or while dequeuing packets and updating conn->sent. KASAN reported: BUG: KASAN: slab-use-after-free in hci_low_sent+0x730/0x840 Workqueue: hci0 hci_tx_work Call Trace: hci_low_sent+0x730/0x840 hci_sched_iso+0x25e/0x4d0 hci_tx_work+0x239/0xcb0 Allocated by task 93: __hci_conn_add+0x16f/0x1b40 hci_bind_bis+0x782/0x17b0 hci_connect_bis+0xa0/0x510 iso_sock_connect+0x589/0x1050 Freed by task 88: kfree+0x131/0x3c0 device_release+0xc8/0x240 kobject_put+0x14d/0x280 hci_conn_del+0x55a/0xe80 hci_disconnect_sync+0x156/0x180 hci_abort_conn_sync+0x3e7/0x940 hci_cmd_sync_work+0x13c/0x290 Hold hci_dev_lock() across connection selection and transmission in both SCO and ISO scheduling, serializing them with connection teardown. This also prevents queuing completion timestamps after the connection queues have been purged. Extending RCU across transmission would be unsafe because the transmit path can sleep. Keep the ISO timeout check outside the mutex since hci_link_tx_to() takes it itself. The preceding channel fix already holds this mutex in the ACL and LE schedulers, which call the SCO scheduler between packets. Move the SCO body to __hci_sched_sco(), assert that its caller holds the mutex, and use it directly from these locked paths. Keep a locking hci_sched_sco() wrapper for the direct calls from hci_tx_work(). This avoids recursively acquiring the device mutex while preserving the scheduling order. Remove the obsolete claim that connection removal disables TX.
Severity
No CVSS data available.
Assigner
Linux CNA under the mitre root
CNA scorecard D 53/100 over 7063 records in the last 180 days details
References
Impacted products
Vendor Product Version CPE status
Linux Linux Affected: bf4c63252490ba78fb833cc7acf1a5b1900c970f , < f997e03e2ef58aa7114828c9d924e515a9a1db9c (git)
Affected: bf4c63252490ba78fb833cc7acf1a5b1900c970f , < 101825c09ad6b7daa6cf4c9e6b1720b13de15596 (git)
Affected: bf4c63252490ba78fb833cc7acf1a5b1900c970f , < 1681f97afdf92e8557f2f3118ddc898471b5d299 (git)
Affected: bf4c63252490ba78fb833cc7acf1a5b1900c970f , < ecdb1c66d8e14e63731c52d6fbcfa604064913c4 (git)
Affected: bf4c63252490ba78fb833cc7acf1a5b1900c970f , < 848a7a91c7f03675d3bd8db6f7721cbf9cb50e21 (git)
guessed Create a notification for this product.
Linux Linux Affected: 3.3
Unaffected: 0 , < 3.3 (semver)
Unaffected: 6.6.160 , ≤ 6.6.* (semver)
Unaffected: 6.12.113 , ≤ 6.12.* (semver)
Unaffected: 6.18.56 , ≤ 6.18.* (semver)
Unaffected: 7.2.10 , ≤ 7.2.* (semver)
Unaffected: 7.3 , ≤ * (original_commit_for_fix)
guessed Create a notification for this product.
Show details on NVD website
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      "cpeApplicability": [
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      "descriptions": [
        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nBluetooth: hci_core: Serialize SCO and ISO scheduling with teardown\n\nhci_low_sent() selects a connection under RCU but drops the read lock\nbefore calculating its quota and returning it to the scheduler. The\nconnection is then used without lifetime protection by hci_sched_iso()\nand hci_sched_sco().\n\nAfter the TX worker drops the RCU read lock, hci_abort_conn_sync() on\nhdev-\u003ereq_workqueue can remove the connection from the hash, complete\nsynchronize_rcu(), purge its queues and release it. The TX worker on\nhdev-\u003eworkqueue can then access the freed connection in hci_quote_sent()\nor while dequeuing packets and updating conn-\u003esent.\n\nKASAN reported:\n\n  BUG: KASAN: slab-use-after-free in hci_low_sent+0x730/0x840\n  Workqueue: hci0 hci_tx_work\n  Call Trace:\n   hci_low_sent+0x730/0x840\n   hci_sched_iso+0x25e/0x4d0\n   hci_tx_work+0x239/0xcb0\n\n  Allocated by task 93:\n   __hci_conn_add+0x16f/0x1b40\n   hci_bind_bis+0x782/0x17b0\n   hci_connect_bis+0xa0/0x510\n   iso_sock_connect+0x589/0x1050\n\n  Freed by task 88:\n   kfree+0x131/0x3c0\n   device_release+0xc8/0x240\n   kobject_put+0x14d/0x280\n   hci_conn_del+0x55a/0xe80\n   hci_disconnect_sync+0x156/0x180\n   hci_abort_conn_sync+0x3e7/0x940\n   hci_cmd_sync_work+0x13c/0x290\n\nHold hci_dev_lock() across connection selection and transmission in both\nSCO and ISO scheduling, serializing them with connection teardown. This\nalso prevents queuing completion timestamps after the connection queues\nhave been purged. Extending RCU across transmission would be unsafe\nbecause the transmit path can sleep. Keep the ISO timeout check outside\nthe mutex since hci_link_tx_to() takes it itself.\n\nThe preceding channel fix already holds this mutex in the ACL and LE\nschedulers, which call the SCO scheduler between packets. Move the SCO\nbody to __hci_sched_sco(), assert that its caller holds the mutex, and\nuse it directly from these locked paths. Keep a locking hci_sched_sco()\nwrapper for the direct calls from hci_tx_work(). This avoids recursively\nacquiring the device mutex while preserving the scheduling order.\n\nRemove the obsolete claim that connection removal disables TX."
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-10-21T12:56:10.088Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
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          "url": "https://git.kernel.org/stable/c/f997e03e2ef58aa7114828c9d924e515a9a1db9c"
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        },
        {
          "url": "https://git.kernel.org/stable/c/848a7a91c7f03675d3bd8db6f7721cbf9cb50e21"
        }
      ],
      "title": "Bluetooth: hci_core: Serialize SCO and ISO scheduling with teardown",
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  "cveMetadata": {
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    "assignerShortName": "Linux",
    "cveId": "CVE-2026-98734",
    "datePublished": "2026-10-18T15:47:12.203Z",
    "dateReserved": "2026-09-25T10:25:14.367Z",
    "dateUpdated": "2026-10-21T12:56:10.088Z",
    "state": "PUBLISHED"
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      "date": "2026-10-27",
      "epss": "0.00168",
      "percentile": "0.05969"
    },
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      "cve": "CVE-2026-98734",
      "id": "msrc_CVE-2026-98734",
      "initial_release_date": "2026-10-20T01:10:41.000Z",
      "product_status:known_affected": "1",
      "product_status:under_investigation": "1",
      "source": "Microsoft CSAF VEX",
      "status": "final",
      "title": "Bluetooth: hci_core: Serialize SCO and ISO scheduling with teardown",
      "url": "https://msrc.microsoft.com/csaf/vex/2026/msrc_cve-2026-98734.json",
      "version": "2"
    },
    "nvd": {
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        "descriptions": [
          {
            "lang": "en",
            "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nBluetooth: hci_core: Serialize SCO and ISO scheduling with teardown\n\nhci_low_sent() selects a connection under RCU but drops the read lock\nbefore calculating its quota and returning it to the scheduler. The\nconnection is then used without lifetime protection by hci_sched_iso()\nand hci_sched_sco().\n\nAfter the TX worker drops the RCU read lock, hci_abort_conn_sync() on\nhdev-\u003ereq_workqueue can remove the connection from the hash, complete\nsynchronize_rcu(), purge its queues and release it. The TX worker on\nhdev-\u003eworkqueue can then access the freed connection in hci_quote_sent()\nor while dequeuing packets and updating conn-\u003esent.\n\nKASAN reported:\n\n  BUG: KASAN: slab-use-after-free in hci_low_sent+0x730/0x840\n  Workqueue: hci0 hci_tx_work\n  Call Trace:\n   hci_low_sent+0x730/0x840\n   hci_sched_iso+0x25e/0x4d0\n   hci_tx_work+0x239/0xcb0\n\n  Allocated by task 93:\n   __hci_conn_add+0x16f/0x1b40\n   hci_bind_bis+0x782/0x17b0\n   hci_connect_bis+0xa0/0x510\n   iso_sock_connect+0x589/0x1050\n\n  Freed by task 88:\n   kfree+0x131/0x3c0\n   device_release+0xc8/0x240\n   kobject_put+0x14d/0x280\n   hci_conn_del+0x55a/0xe80\n   hci_disconnect_sync+0x156/0x180\n   hci_abort_conn_sync+0x3e7/0x940\n   hci_cmd_sync_work+0x13c/0x290\n\nHold hci_dev_lock() across connection selection and transmission in both\nSCO and ISO scheduling, serializing them with connection teardown. This\nalso prevents queuing completion timestamps after the connection queues\nhave been purged. Extending RCU across transmission would be unsafe\nbecause the transmit path can sleep. Keep the ISO timeout check outside\nthe mutex since hci_link_tx_to() takes it itself.\n\nThe preceding channel fix already holds this mutex in the ACL and LE\nschedulers, which call the SCO scheduler between packets. Move the SCO\nbody to __hci_sched_sco(), assert that its caller holds the mutex, and\nuse it directly from these locked paths. Keep a locking hci_sched_sco()\nwrapper for the direct calls from hci_tx_work(). This avoids recursively\nacquiring the device mutex while preserving the scheduling order.\n\nRemove the obsolete claim that connection removal disables TX."
          }
        ],
        "id": "CVE-2026-98734",
        "lastModified": "2026-10-21T13:21:40.570",
        "metrics": {},
        "published": "2026-10-18T16:17:27.010",
        "references": [
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            "url": "https://git.kernel.org/stable/c/f997e03e2ef58aa7114828c9d924e515a9a1db9c"
          }
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        "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "vulnStatus": "Received"
      }
    },
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      "aggregate_severity": "Moderate",
      "current_release_date": "2026-10-21T15:18:27+00:00",
      "cve": "CVE-2026-98734",
      "id": "CVE-2026-98734",
      "initial_release_date": "2026-10-18T15:47:12.203000+00:00",
      "product_status:known_affected": "77",
      "source": "Red Hat CSAF VEX",
      "status": "final",
      "title": "kernel: kernel: Denial of Service via use-after-free in Bluetooth connection scheduling",
      "url": "https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-98734.json",
      "version": "3"
    },
    "suse_vex": {
      "aggregate_severity": "moderate",
      "current_release_date": "2026-10-22T23:45:56Z",
      "cve": "CVE-2026-98734",
      "id": "CVE-2026-98734",
      "initial_release_date": "2026-10-22T16:34:57Z",
      "product_status:known_affected": "158",
      "product_status:known_not_affected": "190",
      "source": "SUSE CSAF VEX",
      "status": "interim",
      "title": "SUSE CVE CVE-2026-98734",
      "url": "https://ftp.suse.com/pub/projects/security/csaf-vex/2026/cve-2026-98734.json",
      "version": "3"
    }
  }
}



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