Bug 2436773 (CVE-2026-23089)

Summary: CVE-2026-23089 kernel: ALSA: usb-audio: Fix use-after-free in snd_usb_mixer_free()
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security DevOps Team <prodsec-dev>
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Version: unspecifiedKeywords: Security
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OS: Linux   
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A use-after-free vulnerability was found in the Linux kernel's USB audio driver. When snd_usb_create_mixer() fails, snd_usb_mixer_free() frees mixer->id_elems while controls already added to the sound card still reference this memory. When snd_card_register() later runs, the OSS mixer layer invokes callbacks on these controls, triggering a use-after-free read in get_ctl_value().
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Description OSIDB Bzimport 2026-02-04 17:02:41 UTC 
In the Linux kernel, the following vulnerability has been resolved:

ALSA: usb-audio: Fix use-after-free in snd_usb_mixer_free()

When snd_usb_create_mixer() fails, snd_usb_mixer_free() frees
mixer->id_elems but the controls already added to the card still
reference the freed memory. Later when snd_card_register() runs,
the OSS mixer layer calls their callbacks and hits a use-after-free read.

Call trace:
  get_ctl_value+0x63f/0x820 sound/usb/mixer.c:411
  get_min_max_with_quirks.isra.0+0x240/0x1f40 sound/usb/mixer.c:1241
  mixer_ctl_feature_info+0x26b/0x490 sound/usb/mixer.c:1381
  snd_mixer_oss_build_test+0x174/0x3a0 sound/core/oss/mixer_oss.c:887
  ...
  snd_card_register+0x4ed/0x6d0 sound/core/init.c:923
  usb_audio_probe+0x5ef/0x2a90 sound/usb/card.c:1025

Fix by calling snd_ctl_remove() for all mixer controls before freeing
id_elems. We save the next pointer first because snd_ctl_remove()
frees the current element.
Comment 1 Jon Moroney 2026-02-05 00:28:26 UTC 
Upstream advisory:
https://lore.kernel.org/linux-cve-announce/2026020424-CVE-2026-23089-760f@gregkh/T