CVE-2026-63904: Undefined Security Weakness

In the Linux kernel, the following vulnerability has been resolved:

usb: usbtmc: check URB actual_length for interrupt-IN notifications

USBTMC devices can use an optional interrupt endpoint for notification messages. These typically contain two-byte headers indicating the payload format, but the driver does not check if these headers are present before accessing the data buffers. In cases where the URB actual_length is not enough to fit these headers, the driver will either cause an out-of-bounds read, or consume stale leftover data from a previous notification.

Fix by checking if actual_data contains enough bytes for the headers, otherwise resubmit URB to the interrupt endpoint.