# CVE-2025-40035: Input: uinput - zero-initialize uinput_ff_upload_compat to avoid info leak

> A local attacker can read uninitialized kernel stack memory via the uinput interface due to missing zero-initialization in the ff_effect_compat structure.

- **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:** 28 Oct 2025
- **Updated:** 11 May 2026
- **Also known as:** AZL-68852, BELL-CVE-2025-40035, DEBIAN-CVE-2025-40035, GHSA-8c35-rp3g-c86r, ROOT-OS-DEBIAN-11-CVE-2025-40035, ROOT-OS-UBUNTU-2204-CVE-2025-40035, ROOT-OS-UBUNTU-2404-CVE-2025-40035, UBUNTU-CVE-2025-40035

## What is CVE-2025-40035?

CVE-2025-40035 is a vulnerability in Linux, published on 28 Oct 2025. 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: uinput - zero-initialize uinput_ff_upload_compat to avoid info leak

Struct ff_effect_compat is embedded twice inside
uinput_ff_upload_compat, contains internal padding. In particular, there
is a hole after struct ff_replay to satisfy alignment requirements for
the following union member. Without clearing the structure,
copy_to_user() may leak stack data to userspace.

Initialize ff_up_compat to zero before filling valid fields.

## Which versions are affected by CVE-2025-40035?


## How do I fix CVE-2025-40035?

Apply the vendor's patch.

## Is CVE-2025-40035 being exploited?

There is no known exploitation of CVE-2025-40035 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2025-40035 and fix it if it is affected.

What it is: CVE-2025-40035 is a vulnerability in Linux, published on 28 Oct 2025. 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-2025-40035 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-2025-40035/ (Markdown: https://insights.sbomify.com/CVE-2025-40035/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2025-40035
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2025-40035
- OSV: https://osv.dev/vulnerability/CVE-2025-40035

---
From sbomify Insights: https://insights.sbomify.com/CVE-2025-40035/
Summaries are generated and may contain mistakes; the official description above is the record.