Bug 2513136 (CVE-2026-68085)

Summary: CVE-2026-68085 kernel: Bluetooth: hci_uart: clear HCI_UART_SENDING when write_work is canceled
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security <prodsec-ir-bot>
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Priority: medium    
Version: unspecifiedCC: rhel-process-autobot, watson-tool-maintainers
Target Milestone: ---Keywords: Security
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Hardware: All   
OS: Linux   
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A flaw was found in the Linux kernel's Bluetooth Host Controller Interface (HCI) Universal Asynchronous Receiver/Transmitter (UART) driver. This vulnerability occurs when a Bluetooth device is reopened after a pending write operation was canceled, but an internal flag indicating a pending write is not properly cleared. A local attacker could exploit this to prevent future write operations to the device, leading to a denial of service where Bluetooth functionality for write tasks becomes unresponsive.
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Description OSIDB Bzimport 2026-08-10 12:01:54 UTC 
In the Linux kernel, the following vulnerability has been resolved:

Bluetooth: hci_uart: clear HCI_UART_SENDING when write_work is canceled

HCI_UART_SENDING bit in tx_state means write_work is pending and blocks
queueing it again.  Currently this bit is not cleared when canceling the
work in hci_uart_close(), which blocks future writes when device is
reopened later if write_work was pending.

Fix by clearing HCI_UART_SENDING when canceling the work.

Also make clearing of tx_skb safe by using disable_work_sync +
enable_work instead of just cancel_work_sync.  hci_uart_flush() purges
the proto tx queue so we can cancel the pending write_work there,
instead of doing it just in hci_uart_close().  Re-enable and possibly
requeue the work after queue flush.
Comment 1 gkamathe 2026-08-11 09:57:15 UTC 
Upstream advisory:
https://lore.kernel.org/linux-cve-announce/2026081058-CVE-2026-68085-6ebf@gregkh/T