CVE-2026-74500 in Linux
Summary
by MITRE • 08/15/2026
In the Linux kernel, the following vulnerability has been resolved:
ALSA: usb-audio: fix stack info leak in RME Digiface status
snd_rme_digiface_read_status() reads a four-word status block from the device into an uninitialised on-stack __le32 buf[4] and, whenever the
vendor control-IN transfer does not return a negative error, copies all four words into the caller's status[].
snd_usb_ctl_msg() copies the full requested size back into the caller's buffer regardless of how many bytes the data stage actually delivered:
buf = kmemdup(data, size, GFP_KERNEL); err = usb_control_msg(dev, pipe, request, requesttype, value, index, buf, size, timeout); memcpy(data, buf, size);
usb_control_msg() returns the transferred length on a short control-IN, which is a non-negative value, and writes only that many bytes. The remainder of the copy back is the kmemdup()ed image of the caller's buffer, so a device answering with a short data stage leaves the trailing words of buf[] holding leftover kernel stack. The only guard
in the caller is err < 0, so those words are stored into status[].
They then reach user space: snd_rme_digiface_get_status_val() selects a 16-bit halfword of status[] per the control's reg/mask, and the eight
Digiface status controls together expose the whole 16-byte frame to an unprivileged reader of /dev/snd/controlC*.
Zero-initialise the buffer so a short read yields zeros instead of stack residue. This mirrors snd_rme_get_status1(), which already clears its output word before the same kind of vendor read.
Discovered by XBOW, triaged by Baul Lee <[email protected]>
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