CVE-2026-90256 (GCVE-0-2026-90256)

Vulnerability from cvelistv5 – Published: 2026-09-17 16:07 – Updated: 2026-10-21 12:50
VLAI
Title
Bluetooth: L2CAP: use proto_lock for l2cap_data to fix l2cap_disconn_ind
Summary
In the Linux kernel, the following vulnerability has been resolved: Bluetooth: L2CAP: use proto_lock for l2cap_data to fix l2cap_disconn_ind hci_conn::l2cap_data is accessed without locks in l2cap_disconn_ind via hci_conn_timeout (disc_work) -> hci_proto_disconn_ind -> l2cap_disconn_ind. This is UAF if the l2cap_conn is deleted concurrently. disc_work is disabled sync in hci_conn_del(), so we cannot take hci_dev_lock in disc_work. Fix by using proto_lock to guard l2cap_data, in addition to hdev->lock which is held in other access paths.
Severity
8.8 (High)
CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Assigner
Linux CNA under the mitre root
CNA scorecard D 53/100 over 6649 records in the last 180 days details
References
Impacted products
Vendor Product Version CPE status
Linux Linux Affected: efc30877bd4bc85fefe98d80af60fafc86e5775e , < 0fa448369c87e20b2aeaeaca0187d698dd61f791 (git)
Affected: f87271d21dd4ee83857ca11b94e7b4952749bbae , < 7c032b6d48a46634cbd58aaebad2638c00ad3b51 (git)
Affected: ab4eedb790cae44313759b50fe47da285e2519d5 , < b495a3a9b33bc4e4613e685bf5c96c136caa22d8 (git)
Affected: ab4eedb790cae44313759b50fe47da285e2519d5 , < 2b66c83ff1751d6bd3201b3017206262ab46dc05 (git)
Affected: 18ab6b6078fa8191ca30a3065d57bf35d5635761 (git)
Affected: 6.6.84 , < 6.6.160 (semver)
Affected: 6.12.20 , < 6.12.114 (semver)
Affected: 6.13.8 , < 6.14 (semver)
guessed Create a notification for this product.
Linux Linux Affected: 6.14
Unaffected: 0 , < 6.14 (semver)
Unaffected: 6.6.160 , ≤ 6.6.* (semver)
Unaffected: 6.12.114 , ≤ 6.12.* (semver)
Unaffected: 7.2.6 , ≤ 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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        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nBluetooth: L2CAP: use proto_lock for l2cap_data to fix l2cap_disconn_ind\n\nhci_conn::l2cap_data is accessed without locks in l2cap_disconn_ind via\nhci_conn_timeout (disc_work) -\u003e hci_proto_disconn_ind -\u003e\nl2cap_disconn_ind.  This is UAF if the l2cap_conn is deleted\nconcurrently.\n\ndisc_work is disabled sync in hci_conn_del(), so we cannot take\nhci_dev_lock in disc_work.\n\nFix by using proto_lock to guard l2cap_data, in addition to hdev-\u003elock\nwhich is held in other access paths."
        }
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            "baseSeverity": "HIGH",
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            "version": "3.1"
          },
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              "lang": "en",
              "value": "AV:A - l2cap_disconn_ind() is reached from hci_conn_timeout() (hci_conn.disc_work) via hci_proto_disconn_ind() only for ACL_LINK/LE_LINK; hcon-\u003el2cap_data is installed by l2cap_conn_add() from l2cap_connect_cfm()/l2cap_chan_connect() on that HCI connection, so the triggering peer must be in Bluetooth radio range.\nAC:L - The attacker creates the ACL/LE link so l2cap_conn_add() publishes hcon-\u003el2cap_data, then tears it down so l2cap_conn_del() or the last l2cap_conn_put() from l2cap_chan_destroy() (rfcomm_process_rx on rfcomm_run) frees the object while hci_conn_timeout() reads conn-\u003edisc_reason; both sides are attacker-driven and retryable.\nPR:N - HCI Connection Complete delivers l2cap_connect_cfm() \u2192 l2cap_conn_add() and later disc_work with no host uid or capability check; SDP (PSM 0x0001) and RFCOMM session close on remote disconnect likewise need no pairing, so an unauthenticated Bluetooth peer is enough.\nUI:N - hci_conn_timeout() runs from hdev-\u003eworkqueue after the last hci_conn_drop() once the adapter is powered and connectable; incoming ACL/LE setup, RFCOMM/L2CAP teardown, and the disconnect timer need no per-attack user click.\nS:U - The UAF is of the host kmalloc l2cap_conn used by l2cap_disconn_ind() and only corrupts that kernel\u0027s Bluetooth/HCI state, with no VM, IOMMU, or sandbox boundary crossing.\nC:H - l2cap_disconn_ind() locklessly loads hcon-\u003el2cap_data and reads conn-\u003edisc_reason after l2cap_conn_free() has kfree\u0027d the kmalloc-1k object, so a sprayed replacement discloses kernel heap contents through that dangling pointer.\nI:H - The same freed l2cap_conn can be reallocated under attacker control while hci_conn_timeout() still holds the pointer; heap UAF of this object enables spraying and write/control-flow hijack, and the stale disc_reason is consumed as the HCI abort reason.\nA:H - The syzbot report is a slab-use-after-free read of conn-\u003edisc_reason in l2cap_disconn_ind() from the hci_conn_timeout worker, which oopses or panics the kernel when the freed l2cap_conn slab is touched."
            }
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        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
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        {
          "url": "https://git.kernel.org/stable/c/2b66c83ff1751d6bd3201b3017206262ab46dc05"
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      "title": "Bluetooth: L2CAP: use proto_lock for l2cap_data to fix l2cap_disconn_ind",
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    "datePublished": "2026-09-17T16:07:55.427Z",
    "dateReserved": "2026-09-11T19:38:34.796Z",
    "dateUpdated": "2026-10-21T12:50:40.034Z",
    "state": "PUBLISHED"
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            "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nBluetooth: L2CAP: use proto_lock for l2cap_data to fix l2cap_disconn_ind\n\nhci_conn::l2cap_data is accessed without locks in l2cap_disconn_ind via\nhci_conn_timeout (disc_work) -\u003e hci_proto_disconn_ind -\u003e\nl2cap_disconn_ind.  This is UAF if the l2cap_conn is deleted\nconcurrently.\n\ndisc_work is disabled sync in hci_conn_del(), so we cannot take\nhci_dev_lock in disc_work.\n\nFix by using proto_lock to guard l2cap_data, in addition to hdev-\u003elock\nwhich is held in other access paths."
          }
        ],
        "id": "CVE-2026-90256",
        "lastModified": "2026-10-21T13:20:44.707",
        "metrics": {
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                "attackVector": "ADJACENT_NETWORK",
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    "redhat_vex": {
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      "current_release_date": "2026-10-29T12:21:06+00:00",
      "cve": "CVE-2026-90256",
      "id": "CVE-2026-90256",
      "initial_release_date": "2026-09-17T00:00:00+00:00",
      "product_status:known_affected": "185",
      "product_status:known_not_affected": "93",
      "source": "Red Hat CSAF VEX",
      "status": "final",
      "title": "kernel: Bluetooth: L2CAP: use proto_lock for l2cap_data to fix l2cap_disconn_ind",
      "url": "https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-90256.json",
      "version": "3"
    },
    "suse_vex": {
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      "current_release_date": "2026-10-20T00:40:55Z",
      "cve": "CVE-2026-90256",
      "id": "CVE-2026-90256",
      "initial_release_date": "2026-09-18T00:19:11Z",
      "product_status:known_affected": "163",
      "product_status:known_not_affected": "185",
      "product_status:recommended": "4",
      "source": "SUSE CSAF VEX",
      "status": "interim",
      "title": "SUSE CVE CVE-2026-90256",
      "url": "https://ftp.suse.com/pub/projects/security/csaf-vex/2026/cve-2026-90256.json",
      "version": "6"
    }
  }
}



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