Look up another CVE · open CVE-2026-64490 in the interactive tracker
CVE-2026-64490
ALSA: virtio: Validate control metadata from the device
Published 2026-07-25 (3 months ago) by the Linux kernel CNA. Subsystem sound/virtio. Debian urgency: unimportant.
What to do, per Debian release
Debian's own status for CVE-2026-64490 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 | not affected | 6.1.190-1 | Nothing to do. bookworm never shipped the vulnerable code. |
| Debian 13trixie | fixed | 6.12.96-1 | Update the kernel and reboot. Fixed in 6.12.96-1. A running kernel keeps the old code until the machine restarts. |
| Debian 14forky | fixed | 7.1.4-1 | Update the kernel and reboot. Fixed in 7.1.4-1. A running kernel keeps the old code until the machine restarts. |
| Debian unstablesid | fixed | 7.1.4-1 | Update the kernel and reboot. Fixed in 7.1.4-1. A running kernel keeps the old code until the machine restarts. |
| Debian 12bookworm · linux-6.12 | fixedDLA-4724-1 · 2026-08-07 · text | 6.12.100-1~deb12u1 | Update the kernel and reboot. DLA-4724-1 shipped the fix on 2026-08-07, in 6.12.100-1~deb12u1. A running kernel keeps the old code until the machine restarts. |
The vulnerability
What the bug is
virtio-snd control handling trusts the device-provided control type and value count returned by the device. That metadata is then used directly to index g_v2a_type_map[] in virtsnd_kctl_info(), and to size loops and memcpy() operations in virtsnd_kctl_get() and virtsnd_kctl_put() against fixed-size virtio_snd_ctl_value and snd_ctl_elem_value arrays. A buggy or malicious device can therefore trigger out-of-bounds access by advertising an invalid control type or an oversized value count. Validate control type and count once in virtsnd_kctl_parse_cfg(), before querying enumerated items or exposing the control to ALSA.
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/virtio/virtio_kctl.c
- What this is
- VIRTIO SOUND DRIVERMAINTAINERS section matched on sound/virtio/* · virtualization@lists.linux.dev · Maintained
- Kernel module
- virtio_snd
Check it on the machine
grep -wE 'CONFIG_SND|CONFIG_SND_VIRTIO' /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 virtio_sndPrints 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. The build rule could not be established for 1 release, so nothing is claimed about those.
- bookworm?
- trixie, forky, sid, bookworm · linux-6.12Mnot built on amd64/cloud-amd64, arm64/cloud-arm64
- ?
- not established - no Makefile entry for the affected file
- M
- a module where it is built at all; some flavours do not build it
Where a release above reads "not established", no build rule for the affected file was found in that release's kernel tree. That is a gap in this lookup, not a finding that the code is absent.
- Build switches
- CONFIG_SND, CONFIG_SND_VIRTIO
- 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
- 2026-07-25 (3 months ago)source
- CVSS
- 8.4 high
CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:Hsource recompute it - Attack vector
- local (AV:L)source
- EPSS
- 0.15%, higher than 4.0% of all CVEssource
- CISA KEV
- not listedthe KEV catalogue
- Debian urgency
- unimportantsource
- Subsystem
- sound/virtio
Upstream fixes
The versions the CNA records as introducing and fixing this, and the commit for each. source
| Introduced | Fixed in | Commit |
|---|---|---|
| 6.9 | 6.12.96 | 3243563f99ef |
| 6.9 | 6.18.39 | 5da9742de22d |
| 6.9 | 7.1.4 | 21584672fd69 |
| 6.9 | 7.2 | c77a6cbb36ff |
Debian advisories
| Advisory | Date | Shipped to | Debian |
|---|---|---|---|
| DLA-4724-1 | 2026-08-07 | bookworm 6.12.100-1~deb12u1 | 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 malformed metadata arrives through a locally attached virtio-snd device/backend and reaches vulnerable ALSA callbacks through local control operations. No routable network path or physical attachment is required.
- AC:LAttack complexity, low
- The backend directly controls the type, count, access flags, and returned values, allowing deterministic oversized loops or copies without a race. Repeated control notifications and operations permit reliable triggering and heap grooming.
- PR:NPrivileges required, none
- A malicious virtio backend supplies metadata during device initialization without guest authentication or capability checks. Standard OSS mixer registration or an automatically running audio service can subsequently access the control without the attacker holding guest credentials.
- UI:NUser interaction, none
- No human action is required because OSS mixer construction and normal audio-service enumeration can query or operate newly registered controls automatically. The backend can also generate control-change notifications to provoke further accesses.
- S:UScope, unchanged
- The vulnerable driver and corrupted kernel memory are within the same guest-kernel security authority. This is host-to-guest device exploitation, not a guest-to-host escape or IOMMU-boundary bypass.
- C:HConfidentiality impact, high
- Oversized read operations copy data beyond the fixed 512-byte response into the userspace-returned ALSA value structure, exposing adjacent kernel heap contents. The unchecked type-map index also provides a device-selected out-of-bounds kernel read.
- I:HIntegrity impact, high
- Oversized INTEGER64, ENUMERATED, and BYTES write operations copy control values beyond the 512-byte virtio request payload into adjacent kernel heap objects. This controlled heap corruption can plausibly provide arbitrary modification or control-flow hijacking.
- A:HAvailability impact, high
- Invalid type indices, enormous loops or memcpy lengths, and resulting heap corruption can cause an immediate kernel fault, oops, panic, or hang. The malicious backend can trigger the condition repeatedly.