CVE-2026-50453 Overview
CVE-2026-50453 is an out-of-bounds read vulnerability [CWE-125] in the Windows USB Audio Class driver (usbaudio.sys). An unauthorized attacker with physical access to a target system can exploit this flaw to disclose sensitive information from kernel memory. The vulnerability requires no privileges or user interaction but depends on a physical attack vector, such as connecting a malicious USB audio device to the target machine. Microsoft published details in the Microsoft Security Update Guide.
Critical Impact
Physical attackers can read out-of-bounds kernel memory through a crafted USB audio device, potentially disclosing sensitive information and causing driver-level denial of service.
Affected Products
- Microsoft Windows (USB Audio Class driver usbaudio.sys)
- Systems accepting USB audio device connections
- Endpoints with the vulnerable version of usbaudio.sys loaded
Discovery Timeline
- 2026-07-14 - CVE CVE-2026-50453 published to NVD
- 2026-07-14 - Last updated in NVD database
Technical Details for CVE-2026-50453
Vulnerability Analysis
The flaw resides in usbaudio.sys, the kernel-mode driver responsible for handling USB Audio Class devices on Windows. The driver parses descriptors and control messages supplied by USB audio peripherals during enumeration and operation. Insufficient bounds validation on attacker-controlled fields lets the driver read memory beyond the intended buffer boundary. An attacker connecting a crafted USB device can trigger the out-of-bounds read and cause the driver to return kernel memory contents or crash. Because the driver runs in kernel context, disclosed data may include sensitive kernel structures, pointers useful for defeating ASLR, or fragments of other in-memory content.
Root Cause
The root cause is missing or incorrect boundary validation when the driver processes USB descriptors or class-specific requests originating from an attached device. The vulnerable code path trusts length or offset fields supplied by the peripheral without verifying them against the allocated buffer size. This aligns with the CWE-125 classification for out-of-bounds read.
Attack Vector
Exploitation requires physical proximity. An attacker plugs a malicious or reprogrammed USB device that advertises itself as a USB Audio Class peripheral into the target computer. The device presents malformed descriptors or class-specific control requests during enumeration. When usbaudio.sys parses the crafted data, it reads past the end of a kernel buffer. The result is either information disclosure returned through USB responses or a driver fault impacting availability. No user interaction or authentication is required once the device is connected.
No public proof-of-concept code is available for this vulnerability.
Detection Methods for CVE-2026-50453
Indicators of Compromise
- Unexpected USB Audio Class device enumerations in Windows event logs, particularly on systems where audio peripherals are not typically used.
- Kernel crashes or bugchecks referencing usbaudio.sys in Windows Error Reporting or minidump files.
- USB device connection events from unrecognized vendor or product identifiers on endpoints in restricted environments.
Detection Strategies
- Monitor Windows event logs (Event IDs 20001, 20003) for USB device installation events and correlate with expected hardware inventories.
- Deploy endpoint telemetry that captures USB device plug-in events, including vendor ID, product ID, and device class descriptors.
- Investigate kernel-mode driver faults involving usbaudio.sys as potential exploitation attempts rather than routine hardware failures.
Monitoring Recommendations
- Enable auditing of removable device connections through Group Policy and forward events to a centralized log platform.
- Baseline normal USB audio device usage per host and alert on deviations, especially on servers, kiosks, and high-value workstations.
- Track patch compliance for usbaudio.sys across the fleet and flag hosts running unpatched versions.
How to Mitigate CVE-2026-50453
Immediate Actions Required
- Apply the Microsoft security update referenced in the Microsoft Security Update Guide as soon as testing permits.
- Restrict physical access to systems handling sensitive data, prioritizing servers, executive workstations, and public-facing kiosks.
- Enforce USB device control policies that block unapproved device classes or unknown vendor and product identifiers.
Patch Information
Microsoft has published guidance and updates for CVE-2026-50453 through the Microsoft Security Update Guide. Administrators should identify affected builds, deploy the corresponding cumulative update, and verify usbaudio.sys reports a patched version after installation.
Workarounds
- Use Group Policy or Microsoft Intune to disable installation of USB Audio Class devices where they are not required for business operations.
- Configure BIOS or UEFI settings to disable unused USB ports on high-risk systems.
- Implement physical port blockers or tamper-evident seals on endpoints deployed in unattended or shared environments.
# Example: Block USB Audio Class device installation via Group Policy setting
# Computer Configuration > Administrative Templates > System > Device Installation > Device Installation Restrictions
# Prevent installation of devices that match the USB Audio Class (Class GUID)
# USB Audio Class GUID example: {4d36e96c-e325-11ce-bfc1-08002be10318} (Media class)
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
