CVE-2026-80829 ALSA: usb-audio: fix OOB write in snd_usbmidi_novation_output()
A malicious USB device can trigger an out-of-bounds write in the Linux kernel ALSA driver, potentially allowing local attackers to execute code or escalate privileges.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Local or same network only
- Victim action needed
- A user has to click or open something
- Fix
- Available
What is CVE-2026-80829?
CVE-2026-80829 is a memory corruption vulnerability in Linux, published on 4 Sep 2026. It can only be exploited from the same machine or local network, and only if a user opens a file or follows a link.
Official description
In the Linux kernel, the following vulnerability has been resolved:
ALSA: usb-audio: fix OOB write in snd_usbmidi_novation_output()
snd_usbmidi_novation_output() lays out a two-byte header at transfer_buffer[0..1] and passes &transfer_buffer[2] together with a length of ep->max_transfer - 2 to snd_rawmidi_transmit():
count = snd_rawmidi_transmit(ep->ports[0].substream, &transfer_buffer[2], ep->max_transfer - 2);
ep->max_transfer comes from the output endpoint's wMaxPacketSize via usb_maxpacket(). A malformed or malicious device can advertise a bulk OUT endpoint with a wMaxPacketSize of 1 - the USB core only clamps this value downwards - so ep->max_transfer becomes 1 and the count argument becomes -1.
snd_rawmidi_transmit() passes the negative count on to __snd_rawmidi_transmit_peek(), where "if (count1 > count) count1 = count" leaves count1 negative; get_aligned_size() keeps it negative for a byte-stream substream, so the following memcpy(buffer, ..., count1) runs with a (size_t)-1 length and writes far past the transfer buffer, which was allocated with usb_alloc_coherent(ep->max_transfer).
This is the same class of bug that was fixed for snd_usbmidi_akai_output() in commit 0970274613fb ("ALSA: usb-audio: fix OOB write in snd_usbmidi_akai_output()"); the novation output routine was left unguarded. Bail out when the endpoint cannot hold the two-byte header plus at least one payload byte.
Which versions are affected by CVE-2026-80829?
How do I fix CVE-2026-80829?
Apply the vendor's patch.
Upgrade to the fixed version. Memory-safe languages, compiler hardening and fuzzing prevent most new cases. More about Memory corruption.
Is CVE-2026-80829 being exploited?
There is no known exploitation of CVE-2026-80829 in the wild and no public exploit code.
Sources
Also known as AZL-99621, BELL-CVE-2026-80829, DEBIAN-CVE-2026-80829, GHSA-vx4g-2353-jv9w, UBUNTU-CVE-2026-80829.