Description
In the Linux kernel, the following vulnerability has been resolved:

ALSA: 6fire: bound the MIDI event length from the device

usb6fire_comm_receiver_handler() forwards a MIDI event using a length
byte the device supplies, with no bound and no check that the transfer
delivered that many bytes:

if (!urb->status) {
if (rt->receiver_buffer[0] == 0x10) /* midi in event */
if (midi_rt)
midi_rt->in_received(midi_rt,
rt->receiver_buffer + 2,
rt->receiver_buffer[1]);
}

receiver_buffer is a 64-byte kzalloc() buffer (COMM_RECEIVER_BUFSIZE), so
only 62 bytes follow the two-byte header. receiver_buffer[1] is a u8 the
device chooses, so a device that answers with 0x10 and a length of 0xFF
makes snd_rawmidi_receive() read 255 bytes starting two bytes into a
64-byte object. The bytes past the buffer are handed to userspace
through the rawmidi read path.

urb->actual_length is not consulted either, so a short transfer leaves
both the type byte and the length byte at their previous values and the
handler acts on stale data.

The receiver URB is submitted from usb6fire_comm_init() at probe, so the
read happens on plug with no user action; forwarding to userspace also
needs a MIDI input substream open, since usb6fire_midi_in_received()
only calls snd_rawmidi_receive() when rt->in is set.

KASAN on 7.2.0-rc5 (arm64), single packet from an emulated device:

BUG: KASAN: slab-out-of-bounds in snd_rawmidi_receive
Read of size 255 at addr ffff000009f64682 by task bash/183
__asan_memcpy
snd_rawmidi_receive
usb6fire_midi_in_received [snd_usb_6fire]
usb6fire_comm_receiver_handler [snd_usb_6fire]
Allocated by task 11:
usb6fire_comm_init [snd_usb_6fire]
usb6fire_chip_probe [snd_usb_6fire]
The buggy address is located 2 bytes inside of
allocated 64-byte region [ffff000009f64680, ffff000009f646c0)

Reject the event when the length exceeds the bytes that follow the
header, and require the transfer to have delivered the header plus that
many bytes. The receiver URB is submitted with a 64-byte
transfer_buffer_length, so a genuine device cannot deliver an event
longer than those 62 bytes and nothing valid is dropped.

Discovered by XBOW, triaged by Baul Lee <baul.lee@xbow.com>
Published: 2026-09-11
Score: 6.3 Medium
EPSS: n/a
KEV: No
Impact: n/a
Action: n/a
AI Analysis

Analysis and contextual insights are available on OpenCVE Cloud.

Remediation

No vendor fix or workaround currently provided.

Additional remediation guidance may be available on OpenCVE Cloud.

Tracking

Sign in to view the affected projects.

Advisories

No advisories yet.

History

Sat, 12 Sep 2026 00:15:00 +0000

Type Values Removed Values Added
Weaknesses CWE-125
References
Metrics threat_severity

None

 cvssV3_1

{'score': 6.3, 'vector': 'CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:N/A:H'}

threat_severity

Moderate

Fri, 11 Sep 2026 23:45:00 +0000

Type Values Removed Values Added
Description In the Linux kernel, the following vulnerability has been resolved: ALSA: 6fire: bound the MIDI event length from the device usb6fire_comm_receiver_handler() forwards a MIDI event using a length byte the device supplies, with no bound and no check that the transfer delivered that many bytes: if (!urb->status) { if (rt->receiver_buffer[0] == 0x10) /* midi in event */ if (midi_rt) midi_rt->in_received(midi_rt, rt->receiver_buffer + 2, rt->receiver_buffer[1]); } receiver_buffer is a 64-byte kzalloc() buffer (COMM_RECEIVER_BUFSIZE), so only 62 bytes follow the two-byte header. receiver_buffer[1] is a u8 the device chooses, so a device that answers with 0x10 and a length of 0xFF makes snd_rawmidi_receive() read 255 bytes starting two bytes into a 64-byte object. The bytes past the buffer are handed to userspace through the rawmidi read path. urb->actual_length is not consulted either, so a short transfer leaves both the type byte and the length byte at their previous values and the handler acts on stale data. The receiver URB is submitted from usb6fire_comm_init() at probe, so the read happens on plug with no user action; forwarding to userspace also needs a MIDI input substream open, since usb6fire_midi_in_received() only calls snd_rawmidi_receive() when rt->in is set. KASAN on 7.2.0-rc5 (arm64), single packet from an emulated device: BUG: KASAN: slab-out-of-bounds in snd_rawmidi_receive Read of size 255 at addr ffff000009f64682 by task bash/183 __asan_memcpy snd_rawmidi_receive usb6fire_midi_in_received [snd_usb_6fire] usb6fire_comm_receiver_handler [snd_usb_6fire] Allocated by task 11: usb6fire_comm_init [snd_usb_6fire] usb6fire_chip_probe [snd_usb_6fire] The buggy address is located 2 bytes inside of allocated 64-byte region [ffff000009f64680, ffff000009f646c0) Reject the event when the length exceeds the bytes that follow the header, and require the transfer to have delivered the header plus that many bytes. The receiver URB is submitted with a 64-byte transfer_buffer_length, so a genuine device cannot deliver an event longer than those 62 bytes and nothing valid is dropped. Discovered by XBOW, triaged by Baul Lee <baul.lee@xbow.com>
Title ALSA: 6fire: bound the MIDI event length from the device
First Time appeared Linux
Linux linux Kernel
CPEs cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
Vendors & Products Linux
Linux linux Kernel
References

Subscriptions

Linux Linux Kernel
cve-icon MITRE

Status: PUBLISHED

Assigner: Linux

Published:

Updated: 2026-09-11T19:42:35.751Z

Reserved: 2026-08-26T14:34:25.810Z

Link: CVE-2026-80973

cve-icon Vulnrichment

No data.

cve-icon NVD

Status : Received

Published: 2026-09-11T20:19:03.490

Modified: 2026-09-11T20:19:03.490

Link: CVE-2026-80973

cve-icon Redhat

Severity : Moderate

Publid Date: 2026-09-11T19:42:35Z

Links: CVE-2026-80973 - Bugzilla

cve-icon OpenCVE Enrichment

No data.

Weaknesses