CVE-2026-68443

Executive Summary

CVE-2026-68443 is a use-after-free (UAF) vulnerability in the Linux kernel's hwmon: (gigabyte_waterforce) HID driver, caused by a race condition between in-flight HID input report processing and the driver's probe failure cleanup path. Linux systems running kernel versions 6.8.0, 6.13.0, or 6.19.0 (as tracked by OSV) that bind the Gigabyte Waterforce HID interface — including malicious USB devices that masquerade as this hardware — are affected. Exploitation requires the ability to attach a USB device to the target and can result in kernel memory corruption, denial of service, or local privilege escalation. No CVSS score has been assigned, no public PoC is available, and the CVE is not listed in CISA's Known Exploited Vulnerabilities catalog.

Technical Analysis

The gigabyte_waterforce driver is a Linux hwmon subsystem driver that manages Gigabyte Waterforce all-in-one liquid-cooling devices (pumps/LCD displays) exposed over USB HID. During driver binding, the probe function executes hid_device_io_start(), which enables the HID core to deliver incoming reports to the driver via the hid_input_report() path. The NVD description states a key implementation fact: calling hid_hw_stop() does not stop device IO. In other words, halting the HID hardware does not quiesce or synchronise the input-report delivery path that may already be executing.

This creates a race window. If the probe operation fails at any point after "IO start" has been executed, the driver proceeds to its error/cleanup path and frees driver-private resources while a concurrently executing hid_input_report() callback may still be accessing them. The result is a use-after-free condition: freed memory is referenced by a still-running kernel callback, which can lead to an oops (denial of service) or, under attacker-controlled memory layout, to privilege escalation via reclaiming the freed object.

The patch described in the NVD entry addresses the root cause precisely: call hid_device_io_stop() before hid_hw_stop() during teardown. hid_device_io_stop() is the counterpart of hid_device_io_start(); invoking it first ensures the input-report processing path is synchronised and drained before the hardware is stopped, eliminating the race between hid_input_report() and the resource cleanup.

The attack surface is entirely local/physical. The driver binds to USB HID devices matching the Gigabyte Waterforce identifiers (VID/PID not disclosed in the NVD description). The attacker must be able to attach a device to the target — via a physical USB port, a managed hub, or USB passthrough in a virtualised environment. A malicious device that enumerates with matching HID descriptors forces driver binding and can control the timing and volume of input report delivery to hit the race window. No network-reachable attack surface exists for this flaw; exploitation requires kernel-level interaction through the USB/HID layer. CWE mapping is consistent with CWE-416 (Use After Free) based on the explicit mention of "UAF" in the NVD description, although the CNA listed CWE as N/A.

Exploitation Scenarios

No public PoC is available; the attack chain below is inferred strictly from the vulnerability class and the mechanism described in the NVD description.

1. Reconnaissance / target identification: The attacker identifies a Linux host running an affected kernel (6.8.0, 6.13.0, or 6.19.0 per OSV tracking). On a physical-access scenario, suitable targets include kiosks, laboratory workstations, management consoles, and other machines with accessible USB ports. The attacker may first confirm that the gigabyte_waterforce driver is available/loadable on the target (e.g., via module presence) and that no fix is applied.

2. Triggering the flaw: The attacker attaches a malicious USB device that enumerates as the Gigabyte Waterforce HID device. The kernel binds the gigabyte_waterforce driver, whose probe function calls hid_device_io_start(). The attacker's device then streams HID input reports while the probe is forced to fail (for example, a control request or feature-report exchange fails, returning an error from the probe path). At the vulnerability-class level, any probe failure after IO start is sufficient to expose the race.

3. Race / payload execution: The race is between hid_input_report() (still processing attacker-supplied HID report bytes) and the probe failure cleanup immediately following hid_device_io_start(). Because hid_hw_stop() does not stop device IO, teardown frees driver-private data that the in-flight report handler still references. At the vulnerability-class level (UAF), the attacker can groom the freed object and reclaim it with controlled HID report content, then abuse the dangling reference to corrupt kernel state. The NVD description does not disclose the exact freed object, so the precise write primitive cannot be specified in this report. It is acceptable to note that no public PoC exists and that the exploitation impact ranges from kernel oops to potential arbitrary code execution depending on allocator state and heap grooming.

4. Post-exploitation: Successful exploitation yields kernel privileges on the target host, enabling full system compromise: disabling security modules, installing rootkits/persistence, reading arbitrary memory, and pivoting into internal networks from the compromised host. On multi-user systems where untrusted users have physical USB access, this becomes a pure local privilege escalation vector. In the minimal case, the race produces a kernel oops and availability impact (denial of service) on the targeted machine.

Impact Assessment

The vulnerability affects the Linux kernel's gigabyte_waterforce HID driver, so any Linux distribution shipping kernels 6.8.0, 6.13.0, or 6.19.0 (per OSV, marked "unfixed") with the driver enabled is potentially affected. The blast radius is local to the host: the flaw is not remotely exploitable over the network, and exploitation requires the ability to attach a USB HID device. However, this includes air-gapped systems, which raises the risk for high-security environments that rely on physical isolation.

Business impact depends on deployment context. In data-centre or server environments where USB ports are physically controlled, exposure is low. In environments with public-facing USB ports — kiosks, retail systems, lab equipment, conference-room PCs, or virtual desktop infrastructure with USB passthrough — the impact is significant: an attacker with momentary device access can gain kernel-level code execution or cause persistent denial of service. For mixed-use fleets, this is a local privilege escalation path from "physical access" to "full host compromise," with subsequent lateral movement risk.

Severity context: no CVSS base score or vector has been published (N/A); no CVSS subscores are available to reference. EPSS estimates exploitation probability at 0.00169 (6.6th percentile), indicating low current exploitation likelihood in the wild. The CVE is not present in the CISA KEV catalog, meaning no confirmed exploitation-in-the-wild evidence has been catalogued as of this report. No threat-actor campaigns have been attributed to this CVE.

Detection Guidance

Because CVE-2026-68443 is a local USB/HID driver race, network-based detection is indirect at best. Primary detection is host-based and should focus on kernel log signatures, USB device-enumeration events, module loading activity, and kernel memory-safety failure reports (KASAN/UAF/oops). The rules below target observable artefacts of the probe-failure/UAF condition and, where relevant, post-exploitation behaviour.

Sigma Rule

title: Linux Kernel gigabyte_waterforce Use-After-Free Indicators
id: 3d4d9a2f-6b5e-4f7a-8e2c-cve202668443
status: experimental
description: >
    Detects kernel log messages referencing the gigabyte_waterforce hwmon HID driver
    combined with memory-safety failure signatures (KASAN use-after-free reports,
    kernel oops, general protection faults). Correlates with CVE-2026-68443.
references:
    - https://nvd.nist.gov/vuln/detail/CVE-2026-68443
author: Valters IT Threat Intelligence
date: 2026/06/07
logsource:
    product: linux
    service: kernel
detection:
    selection_driver:
        Keywords:
            - "gigabyte_waterforce"
    selection_failure:
        Keywords:
            - "KASAN"
            - "use-after-free"
            - "BUG:"
            - "Oops"
            - "general protection fault"
            - "RIP: 0010"
    condition: selection_driver and selection_failure
falsepositives:
    - Genuine hardware faults in Waterforce devices exhibiting the same crash signature
    - Adjacent kernel log entries mixing unrelated driver names and crash text
level: high
tags:
    - attack.t1068
    - cve.2026-68443

YARA Rule

rule linux_gigabyte_waterforce_uaf_indicators
{
    meta:
        author      = "Valters IT Threat Intelligence"
        description = "Detects memory-safety failure indicators associated with the gigabyte_waterforce hwmon HID driver in kernel logs, crash dumps, or memory captures"
        reference   = "CVE-2026-68443"
        cve         = "CVE-2026-68443"
    strings:
        $s1 = "gigabyte_waterforce" ascii wide nocase
        $s2 = "hid_hw_stop" ascii wide
        $s3 = "hid_device_io_stop" ascii wide
        $s4 = "use-after-free" ascii wide nocase
        $s5 = "KASAN" ascii wide nocase
        $s6 = "RIP: 0010" ascii wide
        $s7 = "general protection fault" ascii wide nocase
    condition:
        uint16(0) == 0x5A4D or uint32(0) == 0xFEEDFACE or filesize < 100MB
        and $s1
        and ($s2 or $s3)
        and 1 of ($s4, $s5, $s6, $s7)
}

Suricata IDS Rule

Network detection for this local USB flaw is necessarily indirect. The following rule monitors for suspicious outbound beaconing from affected Linux hosts that may indicate post-exploitation command-and-control activity following a successful local compromise.

alert http $HOME_NET any -> $EXTERNAL_NET any (msg:"ET TROJAN Linux Host Potential Post-Exploitation Beacon (CVE-2026-68443)"; flow:established,to_server; content:"GET "; http_method; content:"/"; http_uri; content:"User-Agent|3a| curl/"; http_header; threshold:type both, track by_src, count 6, seconds 300; metadata:attack_target Linux, deployment Perimeter, cve CVE-2026-68443, signature_severity Major; reference:url,nvd.nist.gov/vuln/detail/CVE-2026-68443; sid:202668443; rev:1;)

Note: absence of matching network traffic does not imply absence of exploitation, since the vulnerability itself produces no network signal.

Elastic Detection

The following EQL rule correlates kernel log references to the driver with subsequent memory-safety failure messages within a short time window — the expected signature of a probe-failure UAF.

sequence by host.name with maxspan=5m
  [ any where message : "*gigabyte_waterforce*" ] 
  [ any where message : ("*KASAN*", "*use-after-free*", "*BUG:*", "*Oops*", "*general protection fault*") ]

Splunk SPL Query

(index=linux sourcetype=linux_kernel OR sourcetype=syslog)
  "gigabyte_waterforce"
  ("KASAN" OR "use-after-free" OR "BUG:" OR "Oops" OR "general protection fault")
| table _time host source message
| sort - _time

Correlate with USB device enumeration events to identify the offending peripheral:

(index=linux sourcetype=linux_kernel)
  ("usb" OR "hid-generic")
  ("new" OR "disconnect" OR "probe")
| table _time host message
| search message = "*gigabyte_waterforce*"

Wazuh OSSEC Rule

<group name="kernel,cve-2026-68443,">
  <rule id="100684" level="13" frequency="1">
    <decoded_as>syslog</decoded_as>
    <field name="program_name">kernel</field>
    <match>gigabyte_waterforce</match>
    <regex>KASAN|use-after-free|BUG:|Oops|general protection fault</regex>
    <description>CVE-2026-68443: use-after-free indicators in Linux kernel gigabyte_waterforce driver</description>
    <mitre>
      <id>T1068</id>
    </mitre>
    <group>attack.privilege_escalation,</group>
  </rule>
</group>

Deploy this rule with the Wazuh syslog/kerne log decoder active on Linux endpoints; alert on any occurrence, then triage for USB device insertion history.

Mitigation & Patch Guidance

Patch confidence is 2/4 (CLAIMED) — the patch is reported by a single source (OSV) and is not independently confirmed. Validate the fix in your distribution's source tree before deploying.

1. Immediate mitigations:

   • Disable or blacklist the driver on systems that do not use Gigabyte Waterforce hardware. Prevent module loading via /etc/modprobe.d/ with blacklist gigabyte_waterforce and install gigabyte_waterforce /bin/false, then update initramfs. The vendor lists no official workaround (N/A).
   • Enforce USB device allow-listing with tools such as USBGuard to block unknown HID devices from binding to kernel drivers, particularly in kiosk, lab, and air-gapped environments.
   • Restrict physical access to USB ports on sensitive hosts; disable unused USB ports at the BIOS/firmware level where operationally feasible.
   • In virtualised environments, disable USB passthrough unless explicitly required.

2. Patch / upgrade steps:

   • Monitor your distribution's kernel channel for a backported fix containing the described change (insertion of hid_device_io_stop() before hid_hw_stop() in the driver teardown path).
   • When available, upgrade to the fixed kernel version; verify with modinfo gigabyte_waterforce and the distribution changelog rather than relying solely on the reported commit.
   • Track OSV/NVD for updates to the affected package entries (6.8.0, 6.13.0, 6.19.0 currently marked "unfixed"; OSV-identified affected revision: 42ac68e3d4ba06ad17bc56b790dbccc37e76e0ba).

3. Long-term hardening:

   • Enable kernel memory-safety instrumentation (KASAN) on test fleets to surface UAF conditions before production deployment.
   • Apply kernel hardening configurations: SMAP/SMEP, strict module signing, slab freelist hardening, and kernel lockdown mode for tamper-resistant environments.
   • Treat USB port access as a privileged capability in your threat model; combine physical security controls with host-based USB policy enforcement.
   • Subscribe to Linux kernel CVE/OSV feeds for the affected subsystem (hwmon, HID) to shorten response time for follow-up patches.

References

1. NVD entry: https://nvd.nist.gov/vuln/detail/CVE-2026-68443
2. OSV vulnerability entry (patch source, affected commits): https://osv.dev/vulnerability/CVE-2026-68443
3. Linux kernel hwmon documentation — gigabyte_waterforce driver: https://docs.kernel.org/hwmon/gigabyte_waterforce.html
4. Linux kernel source tree, hwmon subsystem (affected driver): https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/drivers/hwmon
5. CISA Known Exploited Vulnerabilities Catalog (CVE-2026-68443 not listed): https://www.cisa.gov/known-exploited-vulnerabilities-catalog

No threat-actor campaigns or exploit-in-the-wild evidence for CVE-2026-68443 are known at the time of writing.