CVE-2025-37809 in Linux
Summary
by MITRE • 05/08/2025
In the Linux kernel, the following vulnerability has been resolved:
usb: typec: class: Fix NULL pointer access
Concurrent calls to typec_partner_unlink_device can lead to a NULL pointer dereference. This patch adds a mutex to protect USB device pointers and prevent this issue. The same mutex protects both the device pointers and the partner device registration.
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Analysis
by VulDB Data Team • 03/14/2026
The vulnerability identified as CVE-2025-37809 represents a critical NULL pointer dereference issue within the Linux kernel's USB Type-C subsystem. This flaw exists in the usb typec class implementation where concurrent access to typec_partner_unlink_device function can trigger a race condition leading to system instability. The vulnerability specifically impacts the USB Type-C subsystem which is responsible for managing USB Type-C connector states, power delivery negotiations, and device partnerships in modern computing devices. The issue arises from insufficient synchronization mechanisms protecting shared data structures within the kernel's USB Type-C framework, creating a scenario where multiple threads attempting to access or modify partner device information simultaneously can cause the kernel to attempt to dereference a NULL pointer reference.
The technical implementation flaw stems from the lack of proper mutex protection around critical sections that handle USB device pointer management and partner device registration. When multiple concurrent threads invoke typec_partner_unlink_device operations, the absence of adequate locking mechanisms allows one thread to potentially access a device pointer that has already been freed or set to NULL by another concurrent thread. This race condition manifests as a NULL pointer dereference during the device unlinking process, which can result in kernel oops, system crashes, or potentially exploitable conditions. The vulnerability affects the kernel's USB Type-C class driver which is integral to supporting modern USB Type-C ports and devices including power delivery capabilities, data transfer operations, and device enumeration processes. According to CWE-362, this represents a classic race condition vulnerability where concurrent access to shared resources without proper synchronization leads to unpredictable behavior and potential system compromise.
The operational impact of this vulnerability extends across various Linux kernel versions that implement the USB Type-C subsystem, particularly affecting devices with USB Type-C ports including laptops, desktops, and embedded systems. Systems utilizing USB Type-C for power delivery, data transfer, or device connection management are at risk during periods of high concurrent USB Type-C operations. The vulnerability can lead to system crashes, unexpected reboots, or denial of service conditions that disrupt user productivity and system reliability. Attackers could potentially exploit this condition to cause system instability or in combination with other vulnerabilities, create more serious security implications. The issue particularly affects server and workstation environments where USB Type-C devices are frequently connected and disconnected, or where multiple USB Type-C operations occur simultaneously. From an ATT&CK perspective, this vulnerability could be leveraged as part of a broader attack chain involving privilege escalation or system compromise through service disruption or kernel memory corruption.
Mitigation strategies for CVE-2025-37809 involve applying the kernel patch that introduces proper mutex protection around USB device pointer operations and partner device registration. System administrators should prioritize updating kernel versions to include the fix, particularly in environments where USB Type-C functionality is heavily utilized. The patch implements a single mutex that protects both device pointer operations and partner device registration, ensuring exclusive access to these critical resources during concurrent operations. Organizations should also implement monitoring for system crashes or unexpected reboots that might indicate exploitation attempts. Additionally, the vulnerability highlights the importance of proper kernel synchronization mechanisms and race condition prevention in device driver development. Security teams should review their USB Type-C related device configurations and ensure that kernel updates are applied promptly to prevent potential exploitation. The fix aligns with industry best practices for kernel security and demonstrates the critical importance of proper locking mechanisms in concurrent kernel programming environments.