Bug 2507086 (CVE-2026-64487)

Summary: CVE-2026-64487 kernel: ALSA: caiaq: fix out-of-bounds read in the Traktor Kontrol S4 input parser
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security DevOps Team <prodsec-dev>
Status: NEW --- QA Contact:
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Priority: medium    
Version: unspecifiedCC: rhel-process-autobot, watson-tool-maintainers
Target Milestone: ---Keywords: Security
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Hardware: All   
OS: Linux   
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A flaw was found in the Linux kernel's sound subsystem, specifically within the ALSA caiaq driver responsible for handling Traktor Kontrol S4 devices. A local attacker, by providing specially crafted input from a connected device, could exploit an out-of-bounds read vulnerability. This issue arises from incorrect handling of input stream lengths, leading to the system reading beyond its allocated memory buffer. Successful exploitation could result in the disclosure of sensitive information from kernel memory or cause a system crash, leading to a denial of service.
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Description OSIDB Bzimport 2026-07-25 10:04:15 UTC 
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.
Comment 1 TEJ RATHI 2026-07-30 03:54:03 UTC 
Upstream advisory:
https://lore.kernel.org/linux-cve-announce/2026072549-CVE-2026-64487-03f3@gregkh/T