# 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.

- **Severity:** Not scored
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Local or same network only
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 26 Aug 2026
- **Updated:** 26 Aug 2026
- **Also known as:** AZL-97709, BELL-CVE-2026-80566, DEBIAN-CVE-2026-80566, UBUNTU-CVE-2026-80566

## 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.

## Is CVE-2026-80566 being exploited?

There is no known exploitation of CVE-2026-80566 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-80566 and fix it if it is affected.

What it is: 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.
Exploitation: There is no known exploitation of CVE-2026-80566 in the wild and no public exploit code.

Affected product: Linux. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-80566/ (Markdown: https://insights.sbomify.com/CVE-2026-80566/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-80566
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-80566
- OSV: https://osv.dev/vulnerability/CVE-2026-80566

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-80566/
Summaries are generated and may contain mistakes; the official description above is the record.