CVE-2026-80566 Input: hynitron_cstxxx - validate touch count and finger IDs
A missing validation in the Linux kernel hynitron_cstxxx touch driver allows corrupt touch frames to cause state corruption and potential denial of service.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Local or same network only
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-80566?
CVE-2026-80566 is a denial of service vulnerability in Linux, published on 26 Aug 2026. It can only be exploited from the same machine or local network, with no action from the victim.
Official description
In the Linux kernel, the following vulnerability has been resolved:
Input: hynitron_cstxxx - validate touch count and finger IDs
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.
Which versions are affected by CVE-2026-80566?
How do I fix CVE-2026-80566?
Apply the vendor's patch.
Upgrade, then put limits on request size, rate and nesting depth so one client cannot exhaust the service. More about Denial of service.
Is CVE-2026-80566 being exploited?
There is no known exploitation of CVE-2026-80566 in the wild and no public exploit code.
Sources
Also known as AZL-97709, BELL-CVE-2026-80566, DEBIAN-CVE-2026-80566, UBUNTU-CVE-2026-80566.