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CVE-2026-80716
ALSA: pcm: wake linked drain waiters on unlink
Published 2026-08-28 (2 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-2026-80716 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-4777-1 · 2026-09-08 · text | 6.1.187-1 | Update the kernel and reboot. DLA-4777-1 shipped the fix on 2026-09-08, in 6.1.187-1. A running kernel keeps the old code until the machine restarts. |
| Debian 13trixie | fixed | 6.12.105-1 | Update the kernel and reboot. Fixed in 6.12.105-1. A running kernel keeps the old code until the machine restarts. |
| Debian 14forky | fixed | 7.1.8-1 | Update the kernel and reboot. Fixed in 7.1.8-1. A running kernel keeps the old code until the machine restarts. |
| Debian unstablesid | fixed | 7.1.8-1 | Update the kernel and reboot. Fixed in 7.1.8-1. A running kernel keeps the old code until the machine restarts. |
| Debian 12bookworm · linux-6.12 | fixedDLA-4788-1 · 2026-09-19 · text | 6.12.107-1~deb12u1 | Update the kernel and reboot. DLA-4788-1 shipped the fix on 2026-09-19, in 6.12.107-1~deb12u1. A running kernel keeps the old code until the machine restarts. |
The vulnerability
What the bug is
snd_pcm_drain() on a linked stream parks an on-stack wait entry on the drained peer's runtime->sleep, and after schedule_timeout() removes it only if that peer is still found in the caller's group. If group membership changes during the wait and the sleep ends by signal or timeout (so autoremove_wake_function() does not run), finish_wait() is skipped and snd_pcm_drain() returns with the entry still queued on that stream's sleep list; a later wake_up() then walks a freed stack frame. This is reachable by unlinking either the drained or the draining stream. Unlike the close path (snd_pcm_drop() -> snd_pcm_post_stop()), snd_pcm_unlink() never wakes the sleep queues. Wake every group member under the group lock before the membership change, so a linked drainer is released and drops its entry while the streams are still grouped. The window was opened when snd_pcm_link_rwsem stopped being held across the wait and the removal became conditional on group membership (see Fixes). The later switch to finish_wait() kept that conditional removal, so the signal/timeout case remained.
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, sid, bookworm · linux-6.12Mnot 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
- 2026-08-28 (2 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
- 0.12%, higher than 1.9% 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 |
|---|---|---|
| 5.1 | 5.10.265 | c172e4c53321 |
| 5.1 | 5.15.216 | 3035bb784cea |
| 5.1 | 6.1.183 | 1c1b7e8e545c |
| 5.1 | 6.6.151 | e8b784a3f4fb |
| 5.1 | 6.12.103 | e8315330e4ec |
| 5.1 | 6.18.44 | 2940cc3cf43c |
| 5.1 | 7.1.8 | db09bc4ab19c |
| 5.1 | 7.2 | f495b6c4c859 |
Debian advisories
| Advisory | Date | Shipped to | Debian |
|---|---|---|---|
| DLA-4788-1 | 2026-09-19 | bookworm 6.12.107-1~deb12u1 | tracker |
| DLA-4777-1 | 2026-09-08 | bookworm 6.1.187-1 | 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 bug is triggered only via local ALSA PCM character devices (/dev/snd/pcmC*D*) through open/ioctl syscalls (SNDRV_PCM_IOCTL_LINK, UNLINK, DRAIN); snd_pcm_kernel_ioctl does not expose LINK/UNLINK, and there is no network-facing path to this code.
- AC:LAttack complexity, low
- This is a race, but the attacker controls both sides by opening two PCM fds, linking them, blocking one thread in DRAIN, and concurrently UNLINKing or closing the peer; sending a signal or waiting for timeout forces the path where finish_wait() is skipped.
- PR:LPrivileges required, low
- Exploitation requires only a local process able to open and ioctl ALSA PCM nodes (typical desktop/mobile users via the audio group, session ACLs, or equivalent device permissions); no real root, CAP_SYS_ADMIN, or init-namespace privileges are needed.
- UI:NUser interaction, none
- The attacker drives the entire sequence programmatically with their own PCM file descriptors and threads; no victim interaction such as opening a file, mounting a filesystem, or plugging in hardware is required.
- S:UScope, unchanged
- Impact is confined to kernel memory corruption and privilege escalation within the same security authority; this is not a VM escape, IOMMU/DMA boundary bypass, or other cross-scope violation.
- C:HConfidentiality impact, high
- The orphaned wait_queue_entry_t remains on the sleep list after snd_pcm_drain() returns, and a later wake_up() dereferences a freed on-stack wait entry (use-after-free), which can expose kernel stack/memory contents under attacker-controlled timing.
- I:HIntegrity impact, high
- Corrupting the wait-queue list with a stale stack-backed entry gives kernel memory corruption primitives; wake_up() invokes the entry's function pointer from freed stack memory, enabling plausible control-flow hijack and arbitrary write via further heap/stack grooming.
- A:HAvailability impact, high
- A subsequent wake_up() on the poisoned sleep queue walks a freed stack frame and can oops or panic the kernel; even without full exploitation, the UAF reliably threatens system availability on multimedia desktops, kiosks, and embedded devices with ALSA access.