CVE-2026-90033 ALSA: usb-audio: fix OOB write in snd_usbmidi_us122l_output()
A local attacker with physical access can trigger an out-of-bounds write in the Linux kernel USB MIDI driver, potentially leading to code execution or privilege escalation.
- 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-2026-90033?
CVE-2026-90033 is a memory corruption vulnerability in Linux, published on 16 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_us122l_output()
The snd_usbmidi_us122l_output() picks a count of 2 on anything slower than high speed and never relates it to ep->max_transfer. The URB buffer holds exactly max_transfer bytes, so a device declaring a one byte bulk endpoint takes two bytes from snd_rawmidi_transmit(), and the memset that pads the rest computes 1 - 2 in int and wraps to SIZE_MAX.
Only 0x800e and 0x800f are pinned to nine bytes. The US-122MKII at 0x0644:0x8021 falls to the default and takes usb_maxpacket(), which the USB core only clamps downward.
The akai and novation output ops in this file were given the same guard recently. Do the same here.
Which versions are affected by CVE-2026-90033?
How do I fix CVE-2026-90033?
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-2026-90033 being exploited?
There is no known exploitation of CVE-2026-90033 in the wild and no public exploit code.
Sources
Also known as AZL-101543, BELL-CVE-2026-90033, DEBIAN-CVE-2026-90033, GHSA-3999-x38p-c9qg, UBUNTU-CVE-2026-90033.