CVE-2026-80566

What the bug is

The driver allocates max_touch_num input slots, which are indexed from zero through max_touch_num - 1. The current check allows a finger ID equal to max_touch_num to reach cst3xx_report_contact(). While the input core ignores out-of-range slot indices, reporting touch data without a valid slot change corrupts the touch state of the previously active slot. The touch count is read from the controller's report and is used to index the fixed-size report buffer without first checking its range. Reject counts larger than the supported number of touch slots before checking the trailing byte or parsing touch data. Reject finger IDs equal to or greater than max_touch_num, and return immediately when an invalid finger ID is encountered so that corrupt touch frames are discarded instead of reporting partial contact state. The V821 Avaota F1 board configures the vendor driver with one touch slot, so finger ID 1 is already invalid on that device.

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/input/touchscreen/hynitron_cstxxx.c

What this is

INPUT (KEYBOARD, MOUSE, JOYSTICK, TOUCHSCREEN) DRIVERSMAINTAINERS section matched on drivers/input/ · linux-input@vger.kernel.org · Maintained

Check it on the machine

grep -wE 'CONFIG_INPUT|CONFIG_INPUT_TOUCHSCREEN|CONFIG_TOUCHSCREEN_HYNITRON_CSTXXX' /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 does not build this code in 4 releases. The build rule could not be established for 1 release, so nothing is claimed about those.

• bookworm?
• trixie, forky, sid, bookworm · linux-6.12n

?

not established - no Makefile entry for the affected file

n

not enabled on any flavour - this release does not build the code

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_INPUT, CONFIG_INPUT_TOUCHSCREEN, CONFIG_TOUCHSCREEN_HYNITRON_CSTXXX

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

2026-08-26 (2 months ago)source

CVSS

no vector published, unrated

Attack vector

not published

EPSS

0.16%, higher than 4.4% of all CVEssource

CISA KEV

not listedthe KEV catalogue

Debian urgency

unimportantsource

Subsystem

drivers/input

Upstream fixes

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

Introduced	Fixed in	Commit
6.2	6.6.153	ec61ca4e3106
6.2	6.12.105	387829ee60de
6.2	6.18.46	38e7d5c1ade0
6.2	7.1.10	51c5503554c8
6.2	7.2	27f380ef0e1d

Debian advisories