CVE-2026-50453 exposes information through an out-of-bounds read in Microsoft’s Windows USB Audio Class driver,
Detailed in Microsoft’s Security Response Center advisory, the vulnerability carries a CVSS 3.1 score of 6.1 and an Important severity rating. Microsoft describes the attacker as unauthorized and requiring neither privileges nor user interaction, but the physical attack vector sharply limits the scenarios in which the bug can be exploited.
The National Vulnerability Database identifies the underlying weakness as CWE-125, an out-of-bounds read. As of July 15, NVD was still awaiting its own enrichment of the record, so the publicly available technical detail remains limited and comes primarily from Microsoft.
That convenience also places Microsoft’s parser directly in the path of information supplied by newly attached hardware. CVE-2026-50453 indicates that specially constructed input can cause the driver to read beyond the intended boundary of a memory buffer.
An out-of-bounds read does not necessarily grant control of the machine. Instead, it may reveal memory contents that the attacker should not be able to access. Such disclosure can expose sensitive process or kernel data, defeat assumptions about memory layout, or supply information useful in a larger exploit chain.
Microsoft’s CVSS vector assigns high impact to confidentiality and availability while assigning no impact to integrity. That combination suggests exploitation may disclose substantial information and potentially disrupt the affected system, but Microsoft has not said that CVE-2026-50453 can directly modify data, install software, or execute attacker-controlled code.
The physical vector is the defining constraint. This is not a network-exploitable USB audio vulnerability, and an attacker cannot trigger it merely by sending traffic to a Windows endpoint. The adversary must be able to interact physically with the target, most plausibly by connecting or presenting a malicious USB device.
Microsoft and the Zero Day Initiative both reported no known public disclosure and no exploitation in the wild when the July updates were released. CISA’s initial SSVC assessment likewise recorded no evidence of exploitation and classified automated exploitation as unlikely.
Microsoft’s published affected ranges include:
Windows 11’s July cumulative updates also contain the correction. Installing the correct July 14 security update—or a later cumulative update that supersedes it—is preferable to treating
The broad product list does not mean every affected machine faces equal operational risk. A locked server in a controlled data center is less exposed to a physical USB attack than a reception PC, classroom workstation, medical cart, conference-room computer, public kiosk, or shared engineering system with reachable ports.
Server Core appears in Microsoft’s affected records because the vulnerable driver exists at the operating-system level. The absence of the full Windows desktop does not, by itself, remove the vulnerable component or make the corresponding security update unnecessary.
Enterprise response should start by identifying machines where outsiders or untrusted users can reach USB ports. Physical access is the prerequisite, not a substitute for remediation, and exposed endpoints should still receive the update through Windows Update for Business, Microsoft Intune, Windows Server Update Services, Configuration Manager, or the organization’s normal patch platform.
Temporary controls are most useful where deployment must be delayed. Administrators can reduce exposure by limiting physical access, blocking unused external ports, controlling removable-device installation through policy, or using endpoint-management rules that permit only approved USB hardware.
Those measures require testing. Broadly disabling USB devices can interfere with keyboards, mice, smart-card readers, conferencing equipment, assistive technology, specialist audio hardware, and support workflows. Device-installation restrictions based on hardware identifiers or approved device classes are generally more practical than an indiscriminate USB shutdown.
Removing or renaming
Security teams should also avoid assuming that conventional removable-storage controls cover this case. A USB audio device does not need to present itself as a flash drive, and policies focused solely on USB mass storage may leave other device classes available. The relevant question is whether an untrusted peripheral can be enumerated and processed by the Windows USB stack.
The score is elevated by the potential confidentiality and availability effects and by the lack of required privileges or user interaction. It is tempered by the physical attack vector, unchanged security scope, and absence of direct integrity impact.
The supplied metric language concerning confidence and technical maturity should not be mistaken for proof that exploit details are public. Microsoft has confirmed the vulnerability and identified its root weakness and affected component, but no public proof of concept, exploit procedure, or detailed root-cause analysis was identified at publication time. That means defenders have high confidence that the flaw exists, while would-be attackers still have relatively little public guidance about reproducing it.
CVE-2026-50453 also arrived alongside two other July 2026 information-disclosure fixes in the same USB Audio Class driver: CVE-2026-49794 and CVE-2026-58528. The Zero Day Initiative listed all three as Important and not publicly disclosed or exploited, reinforcing the case for applying the cumulative update rather than attempting to prioritize one
For administrators, the immediate milestone is straightforward: confirm that July 14, 2026 updates have raised affected systems to the fixed build or later, then concentrate compensating controls on endpoints with accessible USB ports. Until Microsoft or independent researchers publish deeper technical analysis, the unresolved issue is not whether the vulnerability exists, but how reliably a malicious USB audio device can turn the out-of-bounds read into useful disclosure or system disruption.
usbaudio.sys, when an attacker has physical access to the computer. Microsoft fixed the flaw in its July 14, 2026 security updates, making prompt deployment the practical response for PCs and servers that accept USB peripherals in public, shared, or otherwise uncontrolled environments.Detailed in Microsoft’s Security Response Center advisory, the vulnerability carries a CVSS 3.1 score of 6.1 and an Important severity rating. Microsoft describes the attacker as unauthorized and requiring neither privileges nor user interaction, but the physical attack vector sharply limits the scenarios in which the bug can be exploited.
The National Vulnerability Database identifies the underlying weakness as CWE-125, an out-of-bounds read. As of July 15, NVD was still awaiting its own enrichment of the record, so the publicly available technical detail remains limited and comes primarily from Microsoft.
A Malicious USB Device Is the Security Boundary
usbaudio.sys is Microsoft’s built-in driver for devices that conform to the USB Audio class specification. Windows loads it automatically when Plug and Play identifies a compatible peripheral, allowing standard speakers, microphones, headsets, audio interfaces, and some MIDI equipment to work without a manufacturer-specific driver.That convenience also places Microsoft’s parser directly in the path of information supplied by newly attached hardware. CVE-2026-50453 indicates that specially constructed input can cause the driver to read beyond the intended boundary of a memory buffer.
An out-of-bounds read does not necessarily grant control of the machine. Instead, it may reveal memory contents that the attacker should not be able to access. Such disclosure can expose sensitive process or kernel data, defeat assumptions about memory layout, or supply information useful in a larger exploit chain.
Microsoft’s CVSS vector assigns high impact to confidentiality and availability while assigning no impact to integrity. That combination suggests exploitation may disclose substantial information and potentially disrupt the affected system, but Microsoft has not said that CVE-2026-50453 can directly modify data, install software, or execute attacker-controlled code.
The physical vector is the defining constraint. This is not a network-exploitable USB audio vulnerability, and an attacker cannot trigger it merely by sending traffic to a Windows endpoint. The adversary must be able to interact physically with the target, most plausibly by connecting or presenting a malicious USB device.
Microsoft and the Zero Day Initiative both reported no known public disclosure and no exploitation in the wild when the July updates were released. CISA’s initial SSVC assessment likewise recorded no evidence of exploitation and classified automated exploitation as unlikely.
Supported Windows Generations Share the Same Driver Risk
The affected-product record spans current Windows 11 releases, supported Windows 10 servicing branches, and several generations of Windows Server. That breadth reflects the long-standing role ofusbaudio.sys as an inbox Windows component rather than a driver installed only with a particular brand of headset or sound card.Microsoft’s published affected ranges include:
- Windows 11 versions 24H2, 25H2, and 26H1 are affected below builds 26100.8875, 26200.8875, and 28000.2269, respectively.
- Windows 10 version 22H2 is affected below build 19045.7548, while version 21H2 is affected below build 19044.7548 where that branch remains serviced.
- Windows 10 version 1809 and Windows Server 2019 are affected below build 17763.9020.
- Windows 10 version 1607 and Windows Server 2016 are affected below build 14393.9339.
- Windows Server 2022 is affected below build 20348.5386.
- Windows Server 2025, including Server Core, is affected below build 26100.33158.
- Windows Server 2012 and Windows Server 2012 R2 are included for customers receiving the applicable extended security updates.
Windows 11’s July cumulative updates also contain the correction. Installing the correct July 14 security update—or a later cumulative update that supersedes it—is preferable to treating
usbaudio.sys as a standalone file that can be replaced independently.The broad product list does not mean every affected machine faces equal operational risk. A locked server in a controlled data center is less exposed to a physical USB attack than a reception PC, classroom workstation, medical cart, conference-room computer, public kiosk, or shared engineering system with reachable ports.
Server Core appears in Microsoft’s affected records because the vulnerable driver exists at the operating-system level. The absence of the full Windows desktop does not, by itself, remove the vulnerable component or make the corresponding security update unnecessary.
Patch First, Restrict Ports Where Physical Access Is Untrusted
For ordinary home users and individually assigned office PCs, installing July’s cumulative security update is the appropriate action. There is no indication that users need to stop using legitimate USB headsets, microphones, or speakers after patching, and Microsoft has not published a special configuration workaround for the flaw.Enterprise response should start by identifying machines where outsiders or untrusted users can reach USB ports. Physical access is the prerequisite, not a substitute for remediation, and exposed endpoints should still receive the update through Windows Update for Business, Microsoft Intune, Windows Server Update Services, Configuration Manager, or the organization’s normal patch platform.
Temporary controls are most useful where deployment must be delayed. Administrators can reduce exposure by limiting physical access, blocking unused external ports, controlling removable-device installation through policy, or using endpoint-management rules that permit only approved USB hardware.
Those measures require testing. Broadly disabling USB devices can interfere with keyboards, mice, smart-card readers, conferencing equipment, assistive technology, specialist audio hardware, and support workflows. Device-installation restrictions based on hardware identifiers or approved device classes are generally more practical than an indiscriminate USB shutdown.
Removing or renaming
usbaudio.sys is not a sound workaround. It is an operating-system component protected and serviced by Windows, and disabling it can break class-compliant audio equipment without addressing other vulnerabilities corrected by the July cumulative update.Security teams should also avoid assuming that conventional removable-storage controls cover this case. A USB audio device does not need to present itself as a flash drive, and policies focused solely on USB mass storage may leave other device classes available. The relevant question is whether an untrusted peripheral can be enumerated and processed by the Windows USB stack.
The Score Needs the Physical Context
A 6.1 CVSS score places CVE-2026-50453 in the medium range under CVSS 3.1, while Microsoft labels it Important under its own severity system. Neither label alone captures the operational difference between a remotely reachable service and a driver flaw that requires someone—or something under their control—to be connected to the machine.The score is elevated by the potential confidentiality and availability effects and by the lack of required privileges or user interaction. It is tempered by the physical attack vector, unchanged security scope, and absence of direct integrity impact.
The supplied metric language concerning confidence and technical maturity should not be mistaken for proof that exploit details are public. Microsoft has confirmed the vulnerability and identified its root weakness and affected component, but no public proof of concept, exploit procedure, or detailed root-cause analysis was identified at publication time. That means defenders have high confidence that the flaw exists, while would-be attackers still have relatively little public guidance about reproducing it.
CVE-2026-50453 also arrived alongside two other July 2026 information-disclosure fixes in the same USB Audio Class driver: CVE-2026-49794 and CVE-2026-58528. The Zero Day Initiative listed all three as Important and not publicly disclosed or exploited, reinforcing the case for applying the cumulative update rather than attempting to prioritize one
usbaudio.sys issue in isolation.For administrators, the immediate milestone is straightforward: confirm that July 14, 2026 updates have raised affected systems to the fixed build or later, then concentrate compensating controls on endpoints with accessible USB ports. Until Microsoft or independent researchers publish deeper technical analysis, the unresolved issue is not whether the vulnerability exists, but how reliably a malicious USB audio device can turn the out-of-bounds read into useful disclosure or system disruption.
References
- Primary source: MSRC
Published: 2026-07-14T07:00:00-07:00
Security Update Guide - Microsoft Security Response Center
msrc.microsoft.com
- Official source: learn.microsoft.com
USB Audio Class System Driver (Usbaudio.sys) - Windows drivers | Microsoft Learn
The USB Audio class system driver (Usbaudio.sys) is an AVStream minidriver that provides driver support for audio devices that comply with the Universal Serial Bus (USB) Device Class Definition for Audio Devices.learn.microsoft.com - Related coverage: ni.com
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There is a file parsing memory corruption vulnerability due to an out-of-bounds write recently discovered in NI LabVIEW that may result in information disclosure or arbitrary code execution. Successful exploitation requires an attacker to get a user to open a specially crafted LV class...www.ni.com
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