CVE-2026-98265

A flaw was found in the Linux kernel's ALSA (Advanced Linux Sound Architecture) USB audio driver. When handling audio devices configured for implicit feedback synchronization, the driver fails to ensure that the received packet count does not exceed the pre-allocated buffer capacity. An attacker capable of connecting a crafted USB audio device can exploit this flaw to cause an out-of-bounds write in kernel memory, resulting in a Denial of Service (DoS) via a system crash or potential privilege escalation.

A heap out of bounds write in ALSA USB audio occurs when an implicit feedback sink replaces the playback URB packet count with a larger packet count calculated from the capture endpoint. A malicious or malformed high speed UAC2 device can advertise mismatched endpoint intervals so that a playback URB allocated for one isochronous descriptor is processed as if it contained eight descriptors. The demonstrated case writes seven descriptors across 112 bytes beyond the allocated heap object and can cause slab corruption and a kernel crash. For the CVSS the PR:N value is used because a malicious USB device does not need an authenticated user account or software privileges on the target after it is attached. The base attack vector is physical for a directly connected USB device. The paranoid attack vector is adjacent because the reproducer uses USB/IP vhci and a hostile exported device may reach the host when USB/IP is configured and the device is attached. Impact is at least denial of service through kernel memory corruption. In the worst defensible case the heap write may affect adjacent kernel objects and could permit confidentiality loss integrity impact or privilege escalation.

The CVSS score(s) listed for this vulnerability do not reflect the associated product's status, and are included for informational purposes to better understand the severity of this vulnerability.

Mitigation for this issue is either not available or the currently available options don't meet the Red Hat Product Security criteria comprising ease of use and deployment, applicability to widespread installation base or stability.