CVE-2026-64487

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

ALSA: caiaq: fix out-of-bounds read in the Traktor Kontrol S4 input parser

snd_usb_caiaq_tks4_dispatch() decodes the Traktor Kontrol S4 input

stream in fixed 16-byte (TKS4_MSGBLOCK_SIZE) message blocks. On every

iteration it advances buf and subtracts the block size while looping on

"while (len)".

len is urb->actual_length. That value is supplied by the device and is

not guaranteed to be a multiple of 16. When a final short block leaves

len between 1 and 15, the loop runs once more, reads up to buf[15], and

then does "len -= TKS4_MSGBLOCK_SIZE". As len is unsigned this underflows

to a huge value. The loop then keeps iterating and walking buf far past

the end of the 512-byte ep4_in_buf, reading out of bounds until a bogus

block id happens to be hit.

Iterate only while a full message block is available. This stops the

unsigned underflow and silently drops any trailing partial block, which

carries no complete control value anyway.

The sibling endpoint-4 parsers are not affected. The Traktor Kontrol X1

and Maschine arms in snd_usb_caiaq_ep4_reply_dispatch() floor

urb->actual_length before dispatching.