CVE-2026-69687 in Windows
Summary
by MITRE • 09/09/2026
Integer underflow (wrap or wraparound) in Windows USB Audio Class driver (usbaudio.sys) allows an authorized attacker to elevate privileges locally.
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Analysis
by VulDB Data Team • 09/09/2026
The vulnerability identified involves a critical integer underflow within the Windows USB Audio Class driver, specifically usbaudio.sys. This component is responsible for managing audio devices connected via Universal Serial Bus interfaces and operates with high system privileges in kernel mode. The flaw arises from improper validation of input parameters during memory allocation or buffer size calculations. When an attacker provides specific crafted inputs that result in a negative value being interpreted as a large unsigned integer, the driver allocates insufficient memory space while subsequently writing data based on the original intended larger size. This discrepancy creates a classic heap-based buffer overflow scenario where write operations exceed the bounds of the allocated buffer, corrupting adjacent memory structures within the kernel address space.
From a technical perspective, this flaw is categorized under CWE-192, which defines integer coercion errors leading to out-of-bounds writes or reads. The mechanism relies on the driver failing to check for negative values before performing arithmetic operations that determine buffer sizes. In Windows operating systems, usbaudio.sys runs at Kernel Level (Ring 0), meaning any memory corruption in this context directly compromises the integrity of the entire system state. An attacker does not need physical access if they can exploit a local service or application with sufficient privileges to trigger the vulnerable code path through USB device enumeration or audio stream manipulation. The exploitation typically involves crafting malicious descriptors or control requests that force the driver into executing the flawed logic, leading to arbitrary memory overwrite capabilities.
The operational impact of this vulnerability is severe due to its potential for Local Privilege Escalation (LPE). By exploiting the heap corruption, an attacker can manipulate kernel pointers such as function addresses in exception handlers or object headers within the Windows Object Manager. This allows the execution of arbitrary code with SYSTEM-level privileges, effectively granting full control over the compromised machine. Such access enables the installation of persistent backdoors, theft of sensitive data including credentials and encryption keys, lateral movement across networked systems, and complete bypassing of security controls like User Account Control (UAC) or Data Execution Prevention (DEP). The attack aligns with MITRE ATT&CK technique T1068, which covers exploitation for privilege escalation, specifically leveraging software vulnerabilities to gain higher-level access.
Mitigation strategies primarily focus on applying the latest cumulative updates provided by Microsoft, as patches typically involve adding strict input validation checks and ensuring proper type casting before arithmetic operations in usbaudio.sys. Administrators should also consider disabling unused USB audio devices if not required for business operations to reduce the attack surface. Additionally, implementing endpoint detection and response solutions can help identify anomalous behavior associated with kernel exploitation attempts, such as unusual memory access patterns or privilege changes originating from driver modules. Regular patch management is critical since this vulnerability exists in widely deployed Windows versions, making it a high-value target for automated malware campaigns seeking initial footholds through local escalation vectors.