CVE-2026-80766 Linux CVE debrief

Who should care

Linux kernel developers and maintainers, Linux distribution maintainers, and users of Linux-based systems should be aware of this vulnerability and take steps to patch their systems. Linux kernel developers and maintainers should review and apply the patch to prevent potential system crashes or instability. Linux distribution maintainers should verify that their kernel versions are up-to-date and patched. Users of Linux-based systems should monitor system

Why it matters

A use-after-free vulnerability in the Linux kernel's HID: uclogic module requires patching to prevent potential system crashes or instability.

• Potential use-after-free errors leading to system crashes or instability
• Possible elevation of privileges or arbitrary code execution
• Required verification of Linux kernel version and patch level
• Necessary monitoring of system logs for potential errors

Technical summary

The uclogic_remove function in the Linux kernel's HID: uclogic module incorrectly orders the shutdown of the pen in-range timer and the device stop. This can lead to a use-after-free error when the timer fires. The fix is to use timer_shutdown_sync before hid_hw_stop. This ensures that the timer is cancelled, waits for a running callback while pen_input is still valid, and prevents any further re-arming. The timer_shutdown_sync function should be used before hid_hw_stop to prevent the use-after-free error. The source code shows that the timer_delete_sync function is used, which only guarantees the timer is idle at that instant, but does not prevent re-arming of the timer.

Defensive priority

Medium

Recommended defensive actions

• Review and apply the patch to the Linux kernel's HID: uclogic module
• Verify that the Linux kernel version is up-to-date and patched
• Monitor system logs for potential use-after-free errors
• 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
• Confirm whether affected product deployments exist in managed environments and assign an owner for follow-up

Evidence notes

The vulnerability is caused by the incorrect ordering of timer shutdown and device stop in the uclogic_remove function. The timer_shutdown_sync function should be used before hid_hw_stop to prevent the use-after-free error. The source code shows that the timer_delete_sync function is used, which only guarantees the timer is idle at that instant, but does not prevent re-arming of the timer. The fix ensures that the timer is provably dead before hid_hw_stop frees the inputs.

Sources and references

Methodology and review provenance

AI-assisted synthesis based on stored public vulnerability evidence. System validation, approval state, and publication status do not by themselves establish human review of this revision. PatchSiren helps prioritize defensive review and does not prove exposure or remediation on any system.