CVE-2026-68085 Linux CVE debrief

Who should care

Linux kernel users and maintainers, Bluetooth hci_uart module developers, and security teams responsible for vulnerability management should be aware of this vulnerability. They should review the supplied official advisory or CVE record to validate affected scope, severity, and vendor guidance. Additionally, they should plan vendor-supported updates or mitigations through normal change control where exposure is confirmed and review compensating controls for exposed systems while remediation is scheduled and verified. Affected product deployments in managed environments need to be confirmed and assigned an owner for follow-up. Relevant monitoring, detection, and logs for exposed assets need to be checked for extra review. Exceptions, retested remediated assets, and closed items should be tracked only after evidence is documented. Operators and platforms using the Linux kernel Bluetooth hci_uart module should also be aware of the potential impact on their systems and take necessary precautions to prevent exploitation. Vulnerability management teams should prioritize patching or mitigating this vulnerability based on the severity and potential impact on their systems. Security teams should also review the CVE record and assess the risk to their organization, considering factors such as asset inventory, exposure, and compensating controls. They should also verify that HCI_UART_SENDING bit handling in Bluetooth hci_uart module is properly cleared when canceling write_work in hci_uart_close(). Security teams should also check for HCI_UART_SENDING bit clearance in hci_uart_flush(). Security teams should review hci_uart_close() and write_work cancellation logic to ensure that future writes are not blocked when the device is reopened. Security teams should also review compensating controls for exposed systems while remediation is scheduled and verified. Security teams should also check relevant monitoring, detection, and logs for exposed assets that need extra review. Security teams should track exceptions, retest remediated assets, and close the item only after evidence is documented. Asset inventory teams should also be aware of the potential impact on their systems.

Technical summary

The Linux kernel Bluetooth hci_uart module has a vulnerability related to HCI_UART_SENDING bit handling. The bit is not cleared when canceling write_work in hci_uart_close(), potentially blocking future writes when the device is reopened. The fix involves clearing HCI_UART_SENDING when canceling the work and making tx_skb safe using disable_work_sync + enable_work. This change ensures that future writes are not blocked when the device is reopened.

Defensive priority

Linux kernel users should verify HCI_UART_SENDING bit handling in Bluetooth hci_uart module.

Recommended defensive actions

• Verify HCI_UART_SENDING bit handling in Bluetooth hci_uart module
• Review hci_uart_close() and write_work cancellation logic
• Check for HCI_UART_SENDING bit clearance in hci_uart_flush()
• Review compensating controls for exposed systems while remediation is scheduled and verified
• Check relevant monitoring, detection, and logs for exposed assets that need extra review
• Track exceptions, retest remediated assets, and close the item only after evidence is documented
• Plan vendor-supported updates or mitigations through normal change control where exposure is confirmed

Evidence notes

The Linux kernel Bluetooth hci_uart module has a vulnerability related to HCI_UART_SENDING bit handling. The bit is not cleared when canceling write_work in hci_uart_close(), potentially blocking future writes when the device is reopened. To verify, defenders should review HCI_UART_SENDING bit handling in Bluetooth hci_uart module, check for HCI_UART_SENDING bit clearance in hci_uart_flush(), and review hci_uart_close() and write_work cancellation logic.

Official resources