CVE-2026-74499 ALSA: usb-audio: fix OOB write in snd_usbmidi_akai_output()
A malicious USB device can trigger a heap out-of-bounds write in the Linux kernel ALSA USB MIDI driver, potentially allowing local privilege escalation or code execution.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Local or same network only
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-74499?
CVE-2026-74499 is a memory corruption vulnerability in Linux, published on 15 Aug 2026. It can only be exploited from the same machine or local network, with no action from the victim.
Official description
In the Linux kernel, the following vulnerability has been resolved:
ALSA: usb-audio: fix OOB write in snd_usbmidi_akai_output()
snd_usbmidi_akai_output() computes its fill-loop bound
buf_end = ep->max_transfer - MAX_AKAI_SYSEX_LEN - 1;
as a signed int, so a small device-advertised bulk-OUT max_transfer makes buf_end negative. The loop guard then compares the u32 urb->transfer_buffer_length against that negative int: the usual arithmetic conversion turns buf_end into a large unsigned value, so the guard stays true and each iteration keeps appending SysEx framing and payload bytes past the end of the URB transfer buffer, which is only max_transfer bytes long.
A USB device that advertises a tiny bulk-OUT endpoint can therefore trigger an attacker-length- and content-controlled heap out-of-bounds write when a process writes to the created /dev/snd/midiC*D* node.
Return early when there is no room for even one SysEx, so the loop is never entered with a bound that would wrap. The loop is the last statement of the function, so bailing out is equivalent to it not running.
Discovered by XBOW, triaged by Baul Lee <baul.lee@xbow.com>
Which versions are affected by CVE-2026-74499?
How do I fix CVE-2026-74499?
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-2026-74499 being exploited?
There is no known exploitation of CVE-2026-74499 in the wild and no public exploit code.
Sources
Also known as AZL-96431, BELL-CVE-2026-74499, DEBIAN-CVE-2026-74499, GHSA-gghh-gc7f-jqch, UBUNTU-CVE-2026-74499.