CVE-2026-68443: Linux Kernel Race Condition Vulnerability

CVE-2026-68443 Overview

CVE-2026-68443 is a use-after-free (UAF) vulnerability in the Linux kernel hwmon subsystem, specifically in the gigabyte_waterforce driver. The flaw stems from a race condition between hid_input_report() and the driver probe function. Calling hid_hw_stop() alone does not halt device input/output operations, leaving a window where the driver may access freed memory if probe fails after hid_device_io_start() has been invoked. The upstream fix calls hid_device_io_stop() before hid_hw_stop() to close the race window.

Critical Impact
A race condition in the gigabyte_waterforce HID driver probe path can lead to a use-after-free condition when probe fails after device I/O has been started.

Affected Products

Linux kernel versions containing the gigabyte_waterforce hwmon driver prior to the fix commits
Systems using Gigabyte Waterforce liquid cooling hardware exposed through the HID hwmon interface
Stable kernel branches referenced by commits 0842e9fa, a855f678, f36e12cc, and ff0c5c53

Discovery Timeline

2026-08-12 - CVE CVE-2026-68443 published to NVD
2026-08-12 - Last updated in NVD database

Technical Details for CVE-2026-68443

Vulnerability Analysis

The vulnerability resides in the gigabyte_waterforce hwmon driver, which manages sensor data from Gigabyte Waterforce all-in-one liquid coolers via the HID (Human Interface Device) transport layer. During driver initialization, the probe function invokes hid_device_io_start() to begin receiving input reports from the connected device.

If probe operations fail after this point, the driver cleanup path calls hid_hw_stop() to release HID resources. However, hid_hw_stop() does not synchronously stop pending device I/O. As a result, hid_input_report() callbacks may continue to execute against driver structures that have already been torn down.

This race condition allows the input report handler to dereference or write to freed memory, producing a classic use-after-free condition [CWE-416]. Kernel UAF conditions can lead to memory corruption, kernel crashes, and under certain circumstances local privilege escalation.

Root Cause

The root cause is an ordering defect in the driver's error-handling path. The driver assumed hid_hw_stop() would quiesce all in-flight input reports. In practice, I/O started via hid_device_io_start() must be explicitly stopped with hid_device_io_stop() before HID hardware teardown. Omitting this call leaves a race window between report delivery and resource release.

Attack Vector

Triggering the flaw requires the probe function to fail after hid_device_io_start() has executed while the device is actively sending input reports. Exploitation is constrained to scenarios where an attacker can influence probe failure conditions for an attached Gigabyte Waterforce HID device. Physical or local access to attach a suitable USB HID device is the most realistic prerequisite. The vulnerability is not remotely exploitable over the network.

No public exploit or proof-of-concept has been published for this issue. For patch details, see the upstream kernel commits: 0842e9fa, a855f678, f36e12cc, and ff0c5c53.

Detection Methods for CVE-2026-68443

Indicators of Compromise

Kernel oops or panic messages referencing gigabyte_waterforce, hid_input_report, or hid_hw_stop in dmesg or /var/log/kern.log
KASAN reports indicating use-after-free in the hwmon HID probe path
Unexpected module load failures for gigabyte_waterforce followed by system instability

Detection Strategies

Enable Kernel Address Sanitizer (KASAN) on test systems to catch UAF conditions in driver probe/teardown paths
Audit installed kernel versions against the fixed commit hashes across the fleet
Monitor kernel ring buffer for repeated HID probe failures on affected hardware

Monitoring Recommendations

Collect and centralize kernel logs from Linux endpoints to identify probe-related crashes
Alert on unexpected kernel module reloads for gigabyte_waterforce or related hwmon drivers
Track USB HID device attach/detach events on systems where Gigabyte Waterforce hardware is not expected

How to Mitigate CVE-2026-68443

Immediate Actions Required

Apply the upstream Linux kernel patches referenced in the stable tree commits and rebuild affected kernels
Update to a distribution kernel release that includes the four fix commits for gigabyte_waterforce
On systems that do not use Gigabyte Waterforce cooling hardware, blacklist the gigabyte_waterforce module to eliminate exposure

Patch Information

The fix modifies the gigabyte_waterforce driver to call hid_device_io_stop() before hid_hw_stop(), ensuring pending input reports are drained before hardware teardown. Patches are available in the stable kernel tree at commits 0842e9faab04, a855f678ba37, f36e12cc8cfe, and ff0c5c53d082. Consult your distribution's security advisories for backported kernel package versions.

Workarounds

Blacklist the gigabyte_waterforce kernel module on systems that do not require it by adding blacklist gigabyte_waterforce to /etc/modprobe.d/blacklist.conf
Restrict physical and USB access on systems where unpatched kernels remain in use
Disable automatic loading of hwmon HID drivers on non-workstation systems where they are unnecessary

bash

# Configuration example: blacklist the vulnerable module until patched
echo "blacklist gigabyte_waterforce" | sudo tee /etc/modprobe.d/disable-gigabyte-waterforce.conf
sudo modprobe -r gigabyte_waterforce 2>/dev/null || true
sudo update-initramfs -u