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CVE-2026-53242
ALSA: PCM: Fix wait queue list corruption in snd_pcm_drain() on linked streams
Published 2026-06-25 (4 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-2026-53242 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 | fixedDLA-4665-1 · 2026-07-03 · text | 6.1.176-1 | Update the kernel and reboot. DLA-4665-1 shipped the fix on 2026-07-03, in 6.1.176-1. A running kernel keeps the old code until the machine restarts. |
| Debian 13trixie | fixed | 6.12.94-1 | Update the kernel and reboot. Fixed in 6.12.94-1. A running kernel keeps the old code until the machine restarts. |
| Debian 14forky | fixed | 7.0.13-1 | Update the kernel and reboot. Fixed in 7.0.13-1. A running kernel keeps the old code until the machine restarts. |
| Debian unstablesid | fixed | 7.0.13-1 | Update the kernel and reboot. Fixed in 7.0.13-1. A running kernel keeps the old code until the machine restarts. |
The vulnerability
What the bug is
snd_pcm_drain() uses init_waitqueue_entry which does not clear entry.prev/next, and add_wait_queue with a conditional remove_wait_queue that is skipped when to_check is no longer in the group after concurrent UNLINK. The orphaned wait entry remains on the unlinked substream sleep queue. On the next drain iteration, add_wait_queue adds the entry to a new queue while still linked on the old one, corrupting both lists. A subsequent wake_up dereferences NULL at the func pointer (mapped from the spinlock at offset 0 of the misinterpreted wait_queue_head_t), causing a kernel panic. Replace init_waitqueue_entry/add_wait_queue/conditional remove_wait_queue with init_wait_entry/prepare_to_wait/ finish_wait. init_wait_entry clears prev/next via INIT_LIST_HEAD on each iteration and sets autoremove_wake_function which auto-removes the entry on wake-up. finish_wait safely handles both the already-removed and still-queued cases.
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/pcm_native.c
- What this is
- SOUNDMAINTAINERS section matched on sound/ · linux-sound@vger.kernel.org · Maintained
- Kernel module
- snd_pcm
Check it on the machine
grep -wE 'CONFIG_SND|CONFIG_SND_PCM' /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_pcmPrints 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_PCM
- 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
- 2026-06-25 (4 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
- 0.13%, higher than 2.4% 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 |
|---|---|---|
| 5.10.253 | 5.10.259 | cac5bf3500ee |
| 5.15.220 | 5.15.220 | 06eca2235a3f |
| 6.1.167 | 6.1.176 | d842f26a167e |
| 6.6.130 | 6.6.143 | d68b621bb5a4 |
| 6.12.78 | 6.12.94 | b053fcd8912f |
| 6.18.19 | 6.18.36 | cd98837db15f |
| 7.0 | 7.0.13 | 7c71a9522555 |
| 7.0 | 7.1 | 88fe2e365872 |
| 6.19.9 | 0 | 0 |
Debian advisories
| Advisory | Date | Shipped to | Debian |
|---|---|---|---|
| DLA-4671-1 | 2026-07-05 | bullseye 6.1.176-1~deb11u1 | tracker |
| DLA-4665-1 | 2026-07-03 | bookworm 6.1.176-1 | tracker |
| DLA-4664-1 | 2026-07-03 | bullseye 5.10.259-1 | tracker |
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 code is reached from local userspace through ALSA PCM character-device ioctls such as SNDRV_PCM_IOCTL_LINK, SNDRV_PCM_IOCTL_UNLINK, and SNDRV_PCM_IOCTL_DRAIN. It is not reachable by remote network packets or adjacent/physical protocols.
- AC:LAttack complexity, low
- The bug is a race, but the attacker can control both sides by using multiple PCM file descriptors/threads to link streams, block in drain, and concurrently unlink. No condition outside attacker control is required once suitable PCM devices are accessible.
- PR:LPrivileges required, low
- No kernel capability check gates the vulnerable ioctl path, but the attacker needs local access to open ALSA PCM device nodes. That corresponds to a basic unprivileged local user with device access, not real root/admin privileges.
- UI:NUser interaction, none
- Exploitation is driven entirely by the attacker's own ioctl calls on opened PCM file descriptors. No victim user action is required.
- S:UScope, unchanged
- The vulnerability is in the kernel ALSA subsystem and affects kernel resources under the same security authority. It is not a VM escape, IOMMU bypass, or other cross-scope boundary violation.
- C:HConfidentiality impact, high
- The documented failure is a panic, but the primitive is kernel wait-queue list corruption with an orphaned stack wait entry and cross-queue linkage under attacker-controlled timing. Under the higher-severity rule, this memory corruption is treated as potentially usable for kernel memory disclosure.
- I:HIntegrity impact, high
- The bug corrupts kernel wait-queue list pointers and can leave stale wait entries reachable by later wakeups. Although the observed path dereferences a NULL function pointer, this is kernel memory corruption plausibly usable for control-flow or privilege-impacting writes, so integrity is High.
- A:HAvailability impact, high
- A subsequent wake_up can dereference a NULL/misinterpreted wait-queue function pointer and panic the kernel. This is a reliable high availability impact.