CVE-2026-20583 in MT6739
Summary
by MITRE • 11/02/2026
In usb, there is a possible system crash due to use after free. This could lead to local denial of service if a malicious actor has already obtained the System privilege. User interaction is not needed for exploitation. Patch ID: ALPS11411916; Issue ID: MSV-9747.
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Analysis
by VulDB Data Team • 11/02/2026
The vulnerability identified under issue identifier MSV-9747 and addressed by patch ALPS11411916 represents a critical memory management flaw within the Universal Serial Bus subsystem of the operating system. This specific defect is classified as a use-after-free error, which occurs when software continues to reference a block of memory after it has been freed or deallocated. In the context of USB device handling, this typically involves driver code that fails to properly nullify pointers or update state flags after releasing resources associated with a disconnected or reset USB peripheral. When the system attempts to access these dangling pointers during subsequent operations such as enumeration, data transfer, or power management events, it triggers undefined behavior within the kernel space. This memory corruption is not merely an application-level error but penetrates deep into the core operating system architecture, compromising the integrity of critical system structures and leading directly to a catastrophic failure state known as a system crash or blue screen of death.
From a technical perspective, this vulnerability aligns with Common Weakness Enumeration identifier CWE-416, which defines use after free conditions where memory is accessed after it has been freed. The root cause lies in the lifecycle management of USB device objects within the kernel driver stack. When a USB device is removed or experiences an error condition that triggers resource cleanup routines, the associated memory buffers and object structures are returned to the system pool. However, if there exists any lingering reference to these resources—perhaps due to asynchronous callbacks, interrupt handlers, or race conditions in thread synchronization—the subsequent dereference of this invalid address results in a fault. Because USB operations often occur at high speeds and involve complex state machines, ensuring that all references are invalidated immediately upon deallocation is challenging but essential for stability. The absence of proper bounds checking or pointer validation allows the system to attempt execution on freed memory pages, which may contain garbage data or have been reallocated for other purposes, thereby corrupting control flow and causing an immediate halt in processing.
The operational impact of this vulnerability is primarily a local denial of service against the affected device's operating environment. As noted in the advisory, exploitation requires that a malicious actor has already obtained System privilege level access to the machine. This constraint significantly limits the attack surface compared to remote or unauthenticated exploits but does not eliminate the threat entirely. An attacker with administrative rights could potentially trigger this condition by manipulating USB devices connected to the system, such as inserting and removing peripherals rapidly or using specialized hardware tools that emulate malicious USB behavior while operating within elevated privileges. The result is a complete loss of availability for all users on the affected machine, requiring a hard reboot to restore functionality. This denial of service can disrupt critical business operations, interrupt ongoing computations, and lead to potential data loss if unsaved work is abruptly terminated by the system crash.
In terms of threat modeling and industry standards, this vulnerability maps to MITRE ATT&CK technique T1499, Endpoint Denial of Service, specifically under methods that involve resource exhaustion or corruption leading to instability. While it does not provide code execution capabilities directly due to the nature of use-after-free crashes in modern protected kernel environments which often trigger security exceptions rather than arbitrary code execution without further exploitation steps, its value lies in reliability disruption and potential privilege escalation vectors if combined with other vulnerabilities. The requirement for System privileges means this is largely an insider threat or post-exploitation scenario where an attacker seeks to cause maximum damage after gaining initial access. Defense-in-depth strategies should focus on minimizing the attack surface by disabling unused USB ports, implementing strict device control policies via endpoint detection and response solutions, and ensuring that all system patches are applied promptly upon release. Regular auditing of driver code for proper memory management practices during development phases is also crucial to prevent such defects from reaching production environments.