{"id":"CVE-2026-63944","title":"Bluetooth: hci_sync: fix UAF in hci_le_create_cis_sync","summary":"In the Linux kernel, the following vulnerability has been resolved:\n\nBluetooth: hci_sync: fix UAF in hci_le_create_cis_sync\n\nhci_le_create_cis_sync() dereferences conn->conn_timeout after releasing\nboth rcu_read_lock() and hci_dev_lock(h…","severity":"high","cvss":8.8,"cvssVector":"CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H","cvssSource":"cna","vendor":"Linux","product":"Linux","affected":["Linux >= c09b80be6ffc338634b2f5f8cfa12b6843410834 < a55618c0f4cead9e59c63f5ee030d393fd70d861","Linux >= c09b80be6ffc338634b2f5f8cfa12b6843410834 < a921957d39290143629eb38c4f74b9bef8035d0a","Linux >= c09b80be6ffc338634b2f5f8cfa12b6843410834 < d9019210c8c30d40eb20094274cc647e352f48f7","Linux >= c09b80be6ffc338634b2f5f8cfa12b6843410834 < 380e67b1794a9a281a0cb592b4e62077fbd0c8ca","Linux >= c09b80be6ffc338634b2f5f8cfa12b6843410834 < bfea6091e0fffb270c20e74384b660910277eb6c","Linux 6.4"],"ssvc":{"exploitation":"none","automatable":"no","technicalImpact":"total","timestamp":"2026-10-16T15:33:58.228611Z"},"published":"2026-07-19","updated":"2026-10-16","sourceUpdated":"2026-10-16T15:42:13.878Z","source":"CVEORG","sourceUrl":"https://www.cve.org/CVERecord?id=CVE-2026-63944","references":[{"url":"https://git.kernel.org/stable/c/a55618c0f4cead9e59c63f5ee030d393fd70d861"},{"url":"https://git.kernel.org/stable/c/a921957d39290143629eb38c4f74b9bef8035d0a"},{"url":"https://git.kernel.org/stable/c/d9019210c8c30d40eb20094274cc647e352f48f7"},{"url":"https://git.kernel.org/stable/c/380e67b1794a9a281a0cb592b4e62077fbd0c8ca"},{"url":"https://git.kernel.org/stable/c/bfea6091e0fffb270c20e74384b660910277eb6c"}],"tags":["cve.org"],"epss":0.00333,"epssPercentile":0.24936,"ingestedAt":"2026-10-16T17:24:46.782Z","slug":"CVE-2026-63944","body":"## Overview\n\nIn the Linux kernel, the following vulnerability has been resolved:\n\nBluetooth: hci_sync: fix UAF in hci_le_create_cis_sync\n\nhci_le_create_cis_sync() dereferences conn->conn_timeout after releasing\nboth rcu_read_lock() and hci_dev_lock(hdev).  The conn pointer was\nobtained from an RCU-protected iteration over hdev->conn_hash.list and\nis not valid once these locks are dropped.  A concurrent disconnect can\nfree the hci_conn between the unlock and the dereference, causing a\nuse-after-free read.\n\nThe cancellation mechanism in hci_conn_del() cannot prevent this because\nhci_le_create_cis_pending() queues hci_create_cis_sync with data=NULL:\n\n    hci_cmd_sync_queue(hdev, hci_create_cis_sync, NULL, NULL);\n\nWhile hci_conn_del() dequeues with data=conn:\n\n    hci_cmd_sync_dequeue(hdev, NULL, conn, NULL);\n\nSince NULL != conn, the lookup in _hci_cmd_sync_lookup_entry() never\nmatches, and the pending work item is not cancelled.\n\nFix this by saving conn->conn_timeout into a local variable while the\nlocks are still held, so the stale conn pointer is never dereferenced\nafter unlock.\n\nThis is the same class of bug as the one fixed by commit 035c25007c9e\n(\"Bluetooth: hci_sync: Fix UAF on le_read_features_complete\") which\naddressed the identical pattern in a different function.\n\nThis vulnerability was identified using 0sec.ai, an open-source\nautomated security auditing platform (https://github.com/0sec-labs).\n\n## Affected\n\n- `Linux >= c09b80be6ffc338634b2f5f8cfa12b6843410834 < a55618c0f4cead9e59c63f5ee030d393fd70d861`\n- `Linux >= c09b80be6ffc338634b2f5f8cfa12b6843410834 < a921957d39290143629eb38c4f74b9bef8035d0a`\n- `Linux >= c09b80be6ffc338634b2f5f8cfa12b6843410834 < d9019210c8c30d40eb20094274cc647e352f48f7`\n- `Linux >= c09b80be6ffc338634b2f5f8cfa12b6843410834 < 380e67b1794a9a281a0cb592b4e62077fbd0c8ca`\n- `Linux >= c09b80be6ffc338634b2f5f8cfa12b6843410834 < bfea6091e0fffb270c20e74384b660910277eb6c`\n- `Linux 6.4`\n\n## Remediation\n\nRefer to the linked advisories for vendor-supplied fixes and affected version ranges.","depth":"twilight","depthScore":48,"depthScoreParts":{"impact":48.4,"likelihood":0.1,"exploitation":0,"ransomware":0},"changes":[]}