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CVE-2026-63930
iio: buffer: hw-consumer: fix use-after-free in error path
Published 2026-07-19 (3 months ago) by the Linux kernel CNA. Subsystem drivers/iio. Debian urgency: not yet assigned.
What to do, per Debian release
Debian's own status for CVE-2026-63930 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 | fixed | 6.1.176-1 | Update the kernel and reboot. Fixed 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 | 7.0.12-1 | Update the kernel and reboot. Fixed in 7.0.12-1. A running kernel keeps the old code until the machine restarts. |
| Debian unstablesid | fixed | 7.0.12-1 | Update the kernel and reboot. Fixed in 7.0.12-1. A running kernel keeps the old code until the machine restarts. |
The vulnerability
What the bug is
In the err_put_buffers cleanup path of iio_hw_consumer_alloc(), the code was using list_for_each_entry() to iterate through buffers while calling iio_buffer_put() which can free the current buffer if refcount drops to 0. The list_for_each_entry() loop macro then evaluates buf->head.next to continue iteration, accessing the freed buffer. Fix this by using list_for_each_entry_safe().
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.
drivers/iio/buffer/industrialio-hw-consumer.c
- What this is
- IIO SUBSYSTEM AND DRIVERSMAINTAINERS section matched on drivers/iio/ · linux-iio@vger.kernel.org · Maintained
- Kernel module
- industrialio_hw_consumer
Check it on the machine
grep -wE 'CONFIG_IIO|CONFIG_IIO_BUFFER_HW_CONSUMER' /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 industrialio_hw_consumerPrints 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.
- bookwormMnot built on amd64/amd64, amd64/cloud-amd64, amd64/rt/amd64, arm64/cloud-arm64, i386/686-pae, i386/rt/686-pae
- trixieMnot built on amd64/amd64, amd64/cloud-amd64, amd64/rt/amd64, arm64/cloud-arm64, armel/rpi, ppc64el/powerpc64le, ppc64el/powerpc64le-64k, riscv64/riscv64, s390x/s390x
- forky, sidMnot built on amd64/amd64, amd64/cloud-amd64, amd64/rt-amd64, arm64/cloud-arm64, loong64/loong64, ppc64el/powerpc64le, ppc64el/powerpc64le-64k, riscv64/riscv64, s390x/s390x
- M
- a module where it is built at all; some flavours do not build it
- Build switches
- CONFIG_IIO, CONFIG_IIO_BUFFER_HW_CONSUMER
- 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
- 2026-07-19 (3 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
- 0.16%, higher than 4.7% of all CVEssource
- CISA KEV
- not listedthe KEV catalogue
- Debian urgency
- not yet assignedsource
- Subsystem
- drivers/iio
Upstream fixes
The versions the CNA records as introducing and fixing this, and the commit for each. source
| Introduced | Fixed in | Commit |
|---|---|---|
| 4.16 | 5.10.259 | b71893c57730 |
| 4.16 | 5.15.210 | 2ff615fc455a |
| 4.16 | 6.1.176 | d2759d49860b |
| 4.16 | 6.6.143 | 29783e6b6ec0 |
| 4.16 | 6.12.93 | e965627f0d44 |
| 4.16 | 6.18.35 | a3763ae33476 |
| 4.16 | 7.0.12 | 9319c94f63ed |
| 4.16 | 7.1 | 6f5ed4f2c7c8 |
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 only reached from kernel driver probe via `devm_iio_hw_consumer_alloc()` in the STM32 DFSDM ADC driver; there is no network, Bluetooth, or direct userspace syscall/ioctl path to `iio_hw_consumer_alloc()`.
- AC:LAttack complexity, low
- Once on affected hardware, triggering the bug requires only causing `ENOMEM` during buffer setup (e.g., memory exhaustion) while probe or deferred-probe runs; the UAF is deterministic on that failure path and does not depend on winning a race or uncontrollable memory layout.
- PR:LPrivileges required, low
- An unprivileged local user can exhaust system memory to force allocation failure during deferred-probe retries on embedded STM32 systems using legacy DFSDM bindings, without requiring init-namespace root or `CAP_SYS_MODULE`.
- UI:NUser interaction, none
- Exploitation does not require any victim user action such as mounting a filesystem or opening a file; memory pressure and kernel probe retries are sufficient.
- S:UScope, unchanged
- Impact is kernel heap memory corruption within the same kernel security authority; this is not a VM escape, IOMMU bypass, or other cross-boundary scope change.
- C:HConfidentiality impact, high
- The bug is a slab use-after-free where the cleanup loop dereferences `buf->head.next` after `iio_buffer_put()` frees the buffer object, enabling arbitrary kernel memory read primitives via heap grooming.
- I:HIntegrity impact, high
- Use-after-free on `hw_consumer_buffer` kmalloc objects can be leveraged for heap corruption and control-flow hijack to achieve arbitrary kernel write or code execution, not merely a bounded modification.
- A:HAvailability impact, high
- The use-after-free dereference of freed list linkage commonly causes kernel oops/panic during the error cleanup path, and successful exploitation can fully compromise kernel availability.