CVE-2026-46073 is a Linux kernel vulnerability in the hwmon (hardware monitoring) subsystem's powerz driver. The flaw occurs because the function wait_for_completion_interruptible_timeout() returns -ERESTARTSYS on signal interrupts, but the original code only handled the timeout case (return 0) to call usb_kill_urb(). When interrupted by a signal, usb_kill_urb() was not called, leading to potential reads from an unfilled USB transfer buffer, which is invalid. The fix involves capturing the return value properly and ensuring usb_kill_urb() is called in both signal and timeout cases before returning. This prevents invalid buffer reads and potential kernel instability. The vulnerability affects many Linux kernel versions prior to 7.0.0-27.27 and is addressed in updated kernel packages. The CVSS v3.1 score is 5.5 (medium severity) with an attack vector of local, low complexity, requiring low privileges, no user interaction, and impacting availability only. No known exploits in the wild have been reported. The vendor advisory from Ubuntu confirms the availability of patches and recommends updating and rebooting systems.

The vulnerability does not affect confidentiality or integrity but impacts availability by potentially causing kernel instability or crashes due to invalid reads from uninitialized USB transfer buffers. An attacker with local access and low privileges could trigger this condition by sending signals during USB operations, leading to denial of service or kernel faults. No data leakage or privilege escalation is indicated.

A patch is available and included in updated Linux kernel packages as per the Ubuntu security advisories USN-8488-1 and USN-8489-1. Users should apply the latest kernel updates and reboot their systems to ensure the fix is applied. Due to an ABI change, recompilation and reinstallation of third-party kernel modules may be required. Follow vendor instructions for updating kernel packages to versions 7.0.0-27.27 or later and corresponding builds. No additional mitigation steps are required beyond applying the official fix.