CVE-2025-38249: 
Linux Kernel vulnerability analysis and mitigation

CVE-2025-38249 is a vulnerability discovered in the Linux kernel's ALSA USB audio subsystem, specifically in the sndusbgetaudioformatuac3() function. The vulnerability was disclosed on July 9, 2025, affecting various Linux distributions and their kernel versions (NVD Database).

The vulnerability stems from improper validation of length values returned from sndusbctlmsg() in the sndusbgetaudioformatuac3() function. The length value, which is controlled by the USB device, is used directly for memory allocation without proper validation. When this allocated buffer is cast to a uac3clusterheaderdescriptor, its fields are accessed without verifying if the buffer is large enough, potentially leading to an out-of-bounds read condition (NVD Database).

The vulnerability affects multiple Linux distributions including Ubuntu 22.04 LTS, 24.04 LTS, and 25.04, as well as various kernel variants such as linux-aws, linux-azure, and linux-gcp. The issue is particularly concerning for systems running affected kernel versions with USB audio devices (Ubuntu Security).

A fix has been implemented by adding a length check to ensure the buffer is large enough for uac3clusterheader_descriptor before accessing its fields. The fix is available in newer kernel versions, and affected distributions are releasing updated packages (Debian Security).