CVE-2025-40085: 
Linux Kernel vulnerability analysis and mitigation

A vulnerability has been identified in the Linux kernel's ALSA USB audio subsystem, tracked as CVE-2025-40085. The issue was discovered and disclosed on October 29, 2025, affecting the USB audio device registration process (NVD).

The vulnerability exists in the trytoregistercard() function of the ALSA USB audio subsystem. The function passes the return value of usbifnumtoif() directly to usbinterfaceclaimed() without performing a NULL check, which can lead to a NULL pointer dereference when processing an invalid USB audio device. The vulnerability has been assigned a CVSS v3.1 base score of 7.0, indicating moderate severity (Red Hat).

When exploited, this vulnerability could lead to a NULL pointer dereference in the Linux kernel when attempting to register an invalid USB audio device. This could potentially result in system crashes or denial of service conditions (NVD).

A fix has been implemented that adds a validation check to ensure the interface pointer is valid before passing it to usbinterfaceclaimed(). This patch has been integrated into the Linux kernel. Affected systems should be updated with the latest kernel version that includes this security fix (NVD).