CVE-2026-52964: ALSA: usb-audio: Bound MIDI 2.0 endpoint descriptor scans

CVE-2026-52964: ALSA: usb-audio: Bound MIDI 2.0 endpoint descriptor scans

[Greg Kroah-Hartman]

From: Greg Kroah-Hartman <gregkh@kernel.org>

Description
===========

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

ALSA: usb-audio: Bound MIDI 2.0 endpoint descriptor scans

The USB MIDI 2.0 endpoint parser has the same descriptor walking
pattern as the legacy MIDI parser. It validates bLength against
bNumGrpTrmBlock before reading baAssoGrpTrmBlkID[], but not against the
remaining bytes in the endpoint-extra scan.

A malformed device can therefore make later baAssoGrpTrmBlkID[] reads
consume bytes past the walked descriptor.

Reject zero-length and overlong descriptors while walking endpoint
extras.

The Linux kernel CVE team has assigned CVE-2026-52964 to this issue.


Affected and fixed versions
===========================

	Issue introduced in 6.5 with commit ff49d1df79aef7580fe3ac99d17c3f886655d080 and fixed in 6.6.141 with commit fafc97bd01e4c737eaeafadfdadb1af4bbfa7307
	Issue introduced in 6.5 with commit ff49d1df79aef7580fe3ac99d17c3f886655d080 and fixed in 6.12.91 with commit a310b4bebda5e4a1b26520c0cc5145ccd6d617e2
	Issue introduced in 6.5 with commit ff49d1df79aef7580fe3ac99d17c3f886655d080 and fixed in 6.18.33 with commit f9c184a83574549a36ea69b755f650e57d164c78
	Issue introduced in 6.5 with commit ff49d1df79aef7580fe3ac99d17c3f886655d080 and fixed in 7.0.10 with commit 17e76b19de1aff5ff4de64d269290bd1b07a01d3
	Issue introduced in 6.5 with commit ff49d1df79aef7580fe3ac99d17c3f886655d080 and fixed in 7.1 with commit 918be519c7876329e1b6e2ea1c59f0b75e792dca

Please see https://www.kernel.org for a full list of currently supported
kernel versions by the kernel community.

Unaffected versions might change over time as fixes are backported to
older supported kernel versions.  The official CVE entry at
	https://cve.org/CVERecord/?id=CVE-2026-52964
will be updated if fixes are backported, please check that for the most
up to date information about this issue.


Affected files
==============

The file(s) affected by this issue are:
	sound/usb/midi2.c


Mitigation
==========

The Linux kernel CVE team recommends that you update to the latest
stable kernel version for this, and many other bugfixes.  Individual
changes are never tested alone, but rather are part of a larger kernel
release.  Cherry-picking individual commits is not recommended or
supported by the Linux kernel community at all.  If however, updating to
the latest release is impossible, the individual changes to resolve this
issue can be found at these commits:
	https://git.kernel.org/stable/c/fafc97bd01e4c737eaeafadfdadb1af4bbfa7307
	https://git.kernel.org/stable/c/a310b4bebda5e4a1b26520c0cc5145ccd6d617e2
	https://git.kernel.org/stable/c/f9c184a83574549a36ea69b755f650e57d164c78
	https://git.kernel.org/stable/c/17e76b19de1aff5ff4de64d269290bd1b07a01d3
	https://git.kernel.org/stable/c/918be519c7876329e1b6e2ea1c59f0b75e792dca