# CVE-2026-98201: Input: zero ff_effect before compat copy in input_ff_effect_from_user

> A local attacker can read uninitialized kernel stack memory via the input subsystem's force feedback compatibility path, potentially leaking sensitive data.

- **Severity:** Not scored
- **Exploited in the wild:** Not known
- **Login needed:** Any signed-in user
- **Attackable:** Local or same network only
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 6 Oct 2026
- **Updated:** 19 Oct 2026
- **Also known as:** AZL-106182, BELL-CVE-2026-98201, DEBIAN-CVE-2026-98201, GHSA-hc65-vq9g-6pfq, UBUNTU-CVE-2026-98201

## What is CVE-2026-98201?

CVE-2026-98201 is a vulnerability in Linux, published on 6 Oct 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: zero ff_effect before compat copy in input_ff_effect_from_user

In the compat path input_ff_effect_from_user() aliases the caller's
native struct ff_effect with the smaller struct ff_effect_compat and
copies only the compat sized prefix:

	compat_effect = (struct ff_effect_compat *)effect;

	if (copy_from_user(compat_effect, buffer,
			   sizeof(struct ff_effect_compat)))

The tail of the native structure is never written. Callers pass an
uninitialized on-stack object, for example evdev_do_ioctl() for
EVIOCSFF, so those bytes keep their previous stack contents.
input_ff_upload() then stores the full native structure in
ff->effects[id], from where a uinput based force feedback daemon can
read it back via UI_BEGIN_FF_UPLOAD, disclosing kernel stack memory to
userspace.

Zero the effect before the compat copy.

## Which versions are affected by CVE-2026-98201?


## How do I fix CVE-2026-98201?

Apply the vendor's patch.

## Is CVE-2026-98201 being exploited?

There is no known exploitation of CVE-2026-98201 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-98201 and fix it if it is affected.

What it is: CVE-2026-98201 is a vulnerability in Linux, published on 6 Oct 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-2026-98201 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-2026-98201/ (Markdown: https://insights.sbomify.com/CVE-2026-98201/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-98201
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-98201
- OSV: https://osv.dev/vulnerability/CVE-2026-98201

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-98201/
Summaries are generated and may contain mistakes; the official description above is the record.