CVE-2026-80886

What the bug is

At the moment, concurrent writes from userspace and the kernel to the console can trigger a race condition that results in an infinite loop of the same messages printed over and over again. This is most likely to happen during system startup or shutdown when the init system starts/stops a large number of system services that interact with various kernel code. When userspace writes to the TTY device, the driver initiates an asynchronous DMA transfer and releases the port lock. At the same moment, the kernel printk path might grab the port lock and re-configure the UART controller for PIO, without waiting for the DMA operation to complete. It seems like this collision results in zero progress being reported for the DMA engine, so the same text is printed to the console over and over again. For the kernel console, we want a reliable output path that will be functional even during crashes etc. So rather than implementing complex code to synchronize the kernel console write routines with the userspace DMA write routines, simply disable DMA for the console UART instance. Similar checks exist in many other serial drivers, e.g. 8250_port.c, imx.c, sh-sci.c etc.

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/tty/serial/msm_serial.c

What this is

ARM/QUALCOMM MAILING LISTMAINTAINERS section matched on drivers/tty/serial/msm_serial.c · linux-arm-msm@vger.kernel.org

Check it on the machine

grep -w CONFIG_SERIAL_MSM /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.

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.

• bookwormYnot built on amd64/amd64, amd64/cloud-amd64, amd64/rt/amd64, armhf/armmp, armhf/armmp-lpae, armhf/rt/armmp, i386/686, i386/686-pae, i386/rt/686-pae, ppc64el/powerpc64le
• trixieYnot built on amd64/amd64, amd64/cloud-amd64, amd64/rt/amd64, armel/rpi, armhf/armmp, armhf/armmp-lpae, armhf/rt/armmp, ppc64el/powerpc64le, ppc64el/powerpc64le-64k, riscv64/riscv64, s390x/s390x
• forky, sidYnot built on amd64/amd64, amd64/cloud-amd64, amd64/rt-amd64, armhf/armmp, armhf/armmp-lpae, loong64/loong64, ppc64el/powerpc64le, ppc64el/powerpc64le-64k, riscv64/riscv64, s390x/s390x

Y

built in where it is built at all; some flavours do not build it

Build switch

CONFIG_SERIAL_MSM

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

2026-09-04 (44 days ago)source

CVSS

no vector published, unrated

Attack vector

not published

EPSS

0.22%, higher than 11.6% of all CVEssource

CISA KEV

not listedthe KEV catalogue

Debian urgency

not yet assignedsource

Subsystem

drivers/tty

Upstream fixes

The versions the CNA records as introducing and fixing this, and the commit for each. source

Introduced	Fixed in	Commit
4.4	5.10.261	f58e568dc308
4.4	5.15.212	bb4296de5b53
4.4	6.1.178	6acea62738ed
4.4	6.6.145	abc1926c88c1
4.4	6.12.97	2727744ccb5c
4.4	6.18.40	d35471624519
4.4	7.1.5	e3b42e326f4f
4.4	7.2	22dd2777e6c1