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CVE-2026-43126
ALSA: mixer: oss: Add card disconnect checkpoints
Published 2026-05-06 (5 months ago) by the Linux kernel CNA. Subsystem sound/core. Debian urgency: not yet assigned.
What to do, per Debian release
Debian's own status for CVE-2026-43126 in every release this site tracks, and what each one means in practice. Every status below is the one the Debian Security Team publishes for this CVE. source
| Release | Status | Version | What this means |
|---|---|---|---|
| Debian 12bookworm | vulnerable | 6.1.190-1 | No fix published anywhere yet, neither in Debian nor upstream for the series bookworm tracks. Watch the Debian tracker page for this CVE. Advisories for bookworm have historically landed a median of 23 days after publication. |
| Debian 13trixie | fixed | 6.12.85-1 | Update the kernel and reboot. Fixed in 6.12.85-1. A running kernel keeps the old code until the machine restarts. |
| Debian 14forky | fixed | 6.19.6-1 | Update the kernel and reboot. Fixed in 6.19.6-1. A running kernel keeps the old code until the machine restarts. |
| Debian unstablesid | fixed | 6.19.6-1 | Update the kernel and reboot. Fixed in 6.19.6-1. A running kernel keeps the old code until the machine restarts. |
The vulnerability
What the bug is
ALSA OSS mixer layer calls the kcontrol ops rather individually, and pending calls might be not always caught at disconnecting the device. For avoiding the potential UAF scenarios, add sanity checks of the card disconnection at each entry point of OSS mixer accesses. The rwsem is taken just before that check, hence the rest context should be covered by that properly.
Where it lives
The fix touches these files. If the subsystem is one you do not use, the practical exposure is lower, though the package is still the vulnerable one.
sound/core/oss/mixer_oss.c
- What this is
- SOUNDMAINTAINERS section matched on sound/ · linux-sound@vger.kernel.org · Maintained
- Kernel module
- snd_mixer_oss
Check it on the machine
grep -wE 'CONFIG_SND|CONFIG_SND_MIXER_OSS|CONFIG_SND_OSSEMUL' /boot/config-$(uname -r)Reads the booted kernel's own configuration, on the machine and nowhere else. =y is built in, =m is a module, and an is not set line means the code is not there.
lsmod | grep -w snd_mixer_ossPrints a line if that module is loaded right now, and nothing if it is not. One that is not loaded can still be loaded later by anything that needs it.
Show whether Debian builds this, per release
Debian builds this, but not on every flavour. At least one release below builds the code on some of its kernel flavours and not on others, so the answer depends on the architecture and flavour installed.
- bookworm, trixie, forky, sidMnot built on amd64/cloud-amd64, arm64/cloud-arm64
- M
- a module where it is built at all; some flavours do not build it
- Build switches
- CONFIG_SND, CONFIG_SND_MIXER_OSS, CONFIG_SND_OSSEMUL
- Reads as
- all on means the file is compiled; any one off means it is not.
From the configuration Debian publishes for every kernel flavour it builds. It covers only the architectures Debian ships a linux-config package for, and nothing about a kernel you built yourself. Debian's own status above stays authoritative about the source package.MAINTAINERS kbuild Makefiles Debian linux-config packages
Signals
- Published
- 2026-05-06 (5 months ago)source
- CVSS
- 7.8 high
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:Hsource recompute it - Attack vector
- local (AV:L)source
- EPSS
- 0.18%, higher than 6.5% of all CVEssource
- CISA KEV
- not listedthe KEV catalogue
- Debian urgency
- not yet assignedsource
- Subsystem
- sound/core
Upstream fixes
The versions the CNA records as introducing and fixing this, and the commit for each. source
| Introduced | Fixed in | Commit |
|---|---|---|
| 2.6.12 | 6.12.75 | ae583f113d15 |
| 2.6.12 | 6.18.16 | e6645e625480 |
| 2.6.12 | 6.19.6 | 8c097cf73699 |
| 2.6.12 | 7.0 | 084d5d444181 |
Why the CNA scored it this way
Quoted from the kernel CNA's own scoring file, word for word. A highlighted metric carries the most severe value CVSS v3.1 defines for it, which is what pushes the score up. source
- AV:LAttack vector, local
- The vulnerable OSS mixer kcontrol paths are reached through local ioctl operations on `/dev/mixer*` or forwarded OSS PCM mixer ioctls. The disconnect side can be induced in a reasonable hotpluggable sound-device scenario while the attacker drives repeated local ioctls.
- AC:LAttack complexity, low
- This is a race, but a local attacker can repeatedly issue mixer ioctls and, in hotplug deployments, control or repeatedly induce the disconnect event. There is no rare memory layout or victim state prerequisite needed to trigger the vulnerable path.
- PR:LPrivileges required, low
- The attacker needs local access to an ALSA OSS mixer or PCM device node, but no kernel capability or real root privilege is checked in the ioctl path. This is basic unprivileged local access where device permissions grant audio-device use.
- UI:NUser interaction, none
- No victim interaction is required once the attacker can run the local ioctl workload and induce the disconnect condition. The attacker controls the operations needed for exploitation.
- S:UScope, unchanged
- The vulnerability is in kernel sound-card handling and impacts the same kernel security authority. It is a standard local kernel compromise or crash scenario, not a VM, IOMMU, or other scope-crossing boundary.
- C:HConfidentiality impact, high
- The fix explicitly addresses potential use-after-free scenarios when OSS mixer code invokes kcontrol callbacks after card shutdown. Per kernel UAF scoring guidance, this can be leveraged for high-impact information disclosure.
- I:HIntegrity impact, high
- The stale kcontrol callback path can operate on freed or disconnected driver state, making this a use-after-free class memory corruption issue. UAF exploitation can provide write/control-flow primitives, so integrity impact is high.
- A:HAvailability impact, high
- Even without full exploitation, invoking kcontrol callbacks after disconnect can dereference freed or invalid device state and crash the kernel. A kernel oops or panic is high availability impact.