CVE-2026-90256 (GCVE-0-2026-90256)
Vulnerability from cvelistv5
Published
2026-09-17 16:07
Modified
2026-10-21 12:50
Severity ?
8.8 (High) - CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
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.
References
Impacted products
Vendor Product Version
Linux Linux Version: efc30877bd4bc85fefe98d80af60fafc86e5775e
Version: f87271d21dd4ee83857ca11b94e7b4952749bbae
Version: ab4eedb790cae44313759b50fe47da285e2519d5
Version: ab4eedb790cae44313759b50fe47da285e2519d5
Version: 18ab6b6078fa8191ca30a3065d57bf35d5635761
Version: 6.6.84   ≤
Version: 6.12.20   ≤
Version: 6.13.8   ≤
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{
  "containers": {
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "net/bluetooth/l2cap_core.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
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              "status": "affected",
              "version": "6.13.8",
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          ]
        },
        {
          "defaultStatus": "affected",
          "product": "Linux",
          "programFiles": [
            "net/bluetooth/l2cap_core.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "6.14"
            },
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              "status": "unaffected",
              "version": "0",
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              "status": "unaffected",
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              "lessThanOrEqual": "6.12.*",
              "status": "unaffected",
              "version": "6.12.114",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "7.2.*",
              "status": "unaffected",
              "version": "7.2.6",
              "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": "6.6.160",
                  "versionStartIncluding": "6.6.84",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.12.114",
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                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "7.2.6",
                  "versionStartIncluding": "6.14",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "7.3",
                  "versionStartIncluding": "6.14",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionStartIncluding": "6.13.8",
                  "vulnerable": true
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              ],
              "negate": false,
              "operator": "OR"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "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."
        }
      ],
      "metrics": [
        {
          "cvssV3_1": {
            "baseScore": 8.8,
            "baseSeverity": "HIGH",
            "vectorString": "CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H",
            "version": "3.1"
          },
          "scenarios": [
            {
              "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."
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-10-21T12:50:40.034Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "references": [
        {
          "url": "https://git.kernel.org/stable/c/0fa448369c87e20b2aeaeaca0187d698dd61f791"
        },
        {
          "url": "https://git.kernel.org/stable/c/7c032b6d48a46634cbd58aaebad2638c00ad3b51"
        },
        {
          "url": "https://git.kernel.org/stable/c/b495a3a9b33bc4e4613e685bf5c96c136caa22d8"
        },
        {
          "url": "https://git.kernel.org/stable/c/2b66c83ff1751d6bd3201b3017206262ab46dc05"
        }
      ],
      "title": "Bluetooth: L2CAP: use proto_lock for l2cap_data to fix l2cap_disconn_ind",
      "x_generator": {
        "engine": "bippy-1.2.0"
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
    "assignerShortName": "Linux",
    "cveId": "CVE-2026-90256",
    "datePublished": "2026-09-17T16:07:55.427Z",
    "dateReserved": "2026-09-11T19:38:34.796Z",
    "dateUpdated": "2026-10-21T12:50:40.034Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}


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