{ "schema_version": "1.6.1", "id": "RPI-CVE-2026-68085", "modified": "2026-10-09T11:39:44Z", "upstream": [ "CVE-2026-68085" ], "published": "2026-08-10T11:51:11Z", "summary": "Bluetooth: hci_uart: clear HCI_UART_SENDING when write_work is canceled", "details": "In the Linux kernel, the following vulnerability has been resolved:\n\nBluetooth: hci_uart: clear HCI_UART_SENDING when write_work is canceled\n\nHCI_UART_SENDING bit in tx_state means write_work is pending and blocks\nqueueing it again. Currently this bit is not cleared when canceling the\nwork in hci_uart_close(), which blocks future writes when device is\nreopened later if write_work was pending.\n\nFix by clearing HCI_UART_SENDING when canceling the work.\n\nAlso make clearing of tx_skb safe by using disable_work_sync +\nenable_work instead of just cancel_work_sync. hci_uart_flush() purges\nthe proto tx queue so we can cancel the pending write_work there,\ninstead of doing it just in hci_uart_close(). Re-enable and possibly\nrequeue the work after queue flush.", "severity": [ { "type": "CVSS_V3", "score": "CVSS:3.1/AV:A/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H" } ], "affected": [ { "package": { "ecosystem": "Raspberry Pi OS:12", "name": "linux" }, "versions": [ "1:6.12.93-1+rpt1" ], "ecosystem_specific": { "binaries": [ { "binary_name": "linux-image-6.12.93+rpt-rpi-2712", "binary_version": "1:6.12.93-1+rpt1" }, { "binary_name": "linux-image-6.12.93+rpt-rpi-v6", "binary_version": "1:6.12.93-1+rpt1" }, { "binary_name": "linux-image-6.12.93+rpt-rpi-v7", "binary_version": "1:6.12.93-1+rpt1" }, { "binary_name": "linux-image-6.12.93+rpt-rpi-v7l", "binary_version": "1:6.12.93-1+rpt1" }, { "binary_name": "linux-image-6.12.93+rpt-rpi-v8", "binary_version": "1:6.12.93-1+rpt1" }, { "binary_name": "linux-image-6.12.93+rpt-rpi-v8-rt", "binary_version": "1:6.12.93-1+rpt1" } ] }, "database_specific": { "per_version": { "1:6.12.93-1+rpt1": { "linux_commit": "d8ab4e908235da7727f22dd36ad5af224671677d", "upstream_version": "6.12.93", "assessment": "commit ancestry (strak rule)", "upstream_fixed": "6.12.96" } } } }, { "package": { "ecosystem": "Raspberry Pi OS:13", "name": "linux" }, "versions": [ "1:6.18.34-1+rpt1" ], "ecosystem_specific": { "binaries": [ { "binary_name": "linux-image-6.18.34+rpt-rpi-2712", "binary_version": "1:6.18.34-1+rpt1" }, { "binary_name": "linux-image-6.18.34+rpt-rpi-v6", "binary_version": "1:6.18.34-1+rpt1" }, { "binary_name": "linux-image-6.18.34+rpt-rpi-v7", "binary_version": "1:6.18.34-1+rpt1" }, { "binary_name": "linux-image-6.18.34+rpt-rpi-v8", "binary_version": "1:6.18.34-1+rpt1" }, { "binary_name": "linux-image-6.18.34+rpt-rpi-v8-rt", "binary_version": "1:6.18.34-1+rpt1" } ] }, "database_specific": { "per_version": { "1:6.18.34-1+rpt1": { "linux_commit": "c8c7494100e99ee05b11aaa4f0588a223a63d1af", "upstream_version": "6.18.34", "assessment": "commit ancestry (strak rule)", "upstream_fixed": "6.18.39" } } } } ], "references": [ { "type": "ADVISORY", "url": "https://www.cve.org/CVERecord?id=CVE-2026-68085" }, { "type": "FIX", "url": "https://git.kernel.org/stable/c/d52446b3e735cfdbdc2a58342163803bc2e64249" }, { "type": "FIX", "url": "https://git.kernel.org/stable/c/b9dd39cf1667e378b25a082ca796d495d578c5d3" }, { "type": "FIX", "url": "https://git.kernel.org/stable/c/714d861d35d937f23375a4517569b13917bbbe51" }, { "type": "FIX", "url": "https://git.kernel.org/stable/c/1b0d946d6f08bd39211385bc703a440911b41e46" } ], "database_specific": { "source": "https://git.kernel.org/pub/scm/linux/security/vulns.git", "upstream_modified": "2026-08-17T05:24:08Z", "severity": { "source": "kernel CNA", "cvss_v3_score": 8.0, "cvss_v3_severity": "High", "scenario": "AV:A - The flaw is in the Bluetooth HCI UART TX teardown path; an adjacent Bluetooth peer can drive HCI traffic to keep write_work pending while privileged stack management (HCIDEVRESET/close during adapter recovery) executes hci_uart_close/flush.\nAC:L - An attacker controls both sides of the race by generating HCI TX to set HCI_UART_SENDING and concurrently triggering adapter close/reset (e.g., HCIDEVRESET), making the stuck-bit and tx_skb teardown races reliably reachable.\nPR:L - Direct exploitation requires CAP_NET_ADMIN to attach the N_HCI TTY line discipline and issue HCIDEVDOWN/HCIDEVRESET ioctls; this capability is available to unprivileged users inside user namespaces, not only init-namespace root.\nUI:N - No victim interaction is required beyond normal Bluetooth operation; exploitation is achieved through attacker-driven HCI traffic and adapter close/reset timing without the user opening files or confirming prompts.\nS:U - Impact is confined to kernel Bluetooth/UART state on the host (permanent TX failure or kernel crash); it does not cross a VM, container, or IOMMU security boundary to affect a different authority.\nC:H - The vulnerable hci_uart_flush path can race with protocol timers requeueing write_work, causing tx_skb double-free/UAF heap corruption that can expose kernel memory contents, not merely a functional TX stall.\nI:H - Concurrent flush and write_work on tx_skb enables heap corruption primitives typical of double-free/UAF bugs in the kernel slab allocator, which can be leveraged for arbitrary memory writes and code execution.\nA:H - Leaving HCI_UART_SENDING set after cancel permanently blocks all future Bluetooth transmissions after reopen until full teardown, and the tx_skb corruption race can trigger kernel oops/panic." } } }