{ "dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": { "cveId": "CVE-2026-90256", "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "state": "PUBLISHED", "assignerShortName": "Linux", "dateReserved": "2026-09-11T19:38:34.796Z", "datePublished": "2026-09-17T16:07:55.427Z", "dateUpdated": "2026-10-19T09:00:32.925Z" }, "containers": { "cna": { "providerMetadata": { "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "shortName": "Linux", "dateUpdated": "2026-10-19T09:00:32.925Z" }, "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) -> hci_proto_disconn_ind ->\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->lock\nwhich is held in other access paths." } ], "metrics": [ { "cvssV3_1": { "version": "3.1", "vectorString": "CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H", "baseScore": 8.8, "baseSeverity": "HIGH" }, "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->l2cap_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->l2cap_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->disc_reason; both sides are attacker-driven and retryable.\nPR:N - HCI Connection Complete delivers l2cap_connect_cfm() → 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->workqueue 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's Bluetooth/HCI state, with no VM, IOMMU, or sandbox boundary crossing.\nC:H - l2cap_disconn_ind() locklessly loads hcon->l2cap_data and reads conn->disc_reason after l2cap_conn_free() has kfree'd 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->disc_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." } ] } ], "affected": [ { "product": "Linux", "vendor": "Linux", "defaultStatus": "unaffected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "net/bluetooth/l2cap_core.c" ], "versions": [ { "version": "ab4eedb790cae44313759b50fe47da285e2519d5", "lessThan": "b495a3a9b33bc4e4613e685bf5c96c136caa22d8", "status": "affected", "versionType": "git" }, { "version": "ab4eedb790cae44313759b50fe47da285e2519d5", "lessThan": "2b66c83ff1751d6bd3201b3017206262ab46dc05", "status": "affected", "versionType": "git" }, { "version": "efc30877bd4bc85fefe98d80af60fafc86e5775e", "status": "affected", "versionType": "git" }, { "version": "f87271d21dd4ee83857ca11b94e7b4952749bbae", "status": "affected", "versionType": "git" }, { "version": "18ab6b6078fa8191ca30a3065d57bf35d5635761", "status": "affected", "versionType": "git" }, { "version": "6.6.84", "lessThan": "6.7", "status": "affected", "versionType": "semver" }, { "version": "6.12.20", "lessThan": "6.13", "status": "affected", "versionType": "semver" }, { "version": "6.13.8", "lessThan": "6.14", "status": "affected", "versionType": "semver" } ] }, { "product": "Linux", "vendor": "Linux", "defaultStatus": "affected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "net/bluetooth/l2cap_core.c" ], "versions": [ { "version": "6.14", "status": "affected" }, { "version": "0", "lessThan": "6.14", "status": "unaffected", "versionType": "semver" }, { "version": "7.2.6", "lessThanOrEqual": "7.2.*", "status": "unaffected", "versionType": "semver" }, { "version": "7.3", "lessThanOrEqual": "*", "status": "unaffected", "versionType": "original_commit_for_fix" } ] } ], "cpeApplicability": [ { "nodes": [ { "operator": "OR", "negate": false, "cpeMatch": [ { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.14", "versionEndExcluding": "7.2.6" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.14", "versionEndExcluding": "7.3" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.6.84" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.12.20" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.13.8" } ] } ] } ], "references": [ { "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" } } } }