Bug 2540451 (CVE-2026-93808)

Summary:	CVE-2026-93808 kernel: ALSA: usb-audio: caiaq: validate EP1 reply lengths
Product:	[Other] Security Response	Reporter:	OSIDB Bzimport <bzimport>
Component:	vulnerability	Assignee:	Product Security DevOps Team <prodsec-dev>
Status:	NEW ---	QA Contact:
Severity:	medium	Docs Contact:
Priority:	medium
Version:	unspecified	CC:	akhatavk, aos-team-art-private, asdas, dpaolell, jdelft, jupierce, lgarciaa, mbiarnes, ppalepu, ppostler, prdhamdh, rhel-process-autobot, sghai, sidsharm, suppawar, vlaad, watson-tool-maintainers
Target Milestone:	---	Keywords:	Security
Target Release:	---
Hardware:	All
OS:	Linux
Whiteboard:
Fixed In Version:		Doc Type:	---
Doc Text:	A flaw was found in the Linux kernel's ALSA (Advanced Linux Sound Architecture) caiaq USB audio driver. When processing endpoint reply messages, the driver fails to validate the length of received USB data buffers before reading fixed offsets. A physically present attacker connecting a crafted USB device could exploit this flaw to cause an out-of-bounds memory read, leading to a system crash and Denial of Service (DoS).	Story Points:	---
Clone Of:		Environment:
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Regression:	---	Mount Type:	---
Documentation:	---	CRM:
Verified Versions:		Category:	---
oVirt Team:	---	RHEL 7.3 requirements from Atomic Host:
Cloudforms Team:	---	Target Upstream Version:
Embargoed:

Description OSIDB Bzimport 2026-09-24 16:53:06 UTC

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

ALSA: usb-audio: caiaq: validate EP1 reply lengths

usb_ep1_command_reply_dispatch() uses buf[0] as a command byte and then
reads command-specific fixed items from the same URB buffer. Several
paths use buf + 1, buf[1], buf[2], or buf + 3 without first proving that
urb->actual_length contains those bytes.

Add per-command length checks, use a payload length derived from the
bytes after the command byte for the control-state copy, and reject short
analog input payloads before the input helper reads fixed offsets from
the EP1 reply.

Comment 1 Mauro Matteo Cascella 2026-09-28 12:56:30 UTC

Upstream advisory:
https://git.kernel.org/pub/scm/linux/security/vulns.git/plain/cve/published/2026/CVE-2026-93808.mbox