# RUSTSEC-2025-0169: `FormatContext` stream accessors can cause undefined behavior from safe code

> Safe Rust code can trigger undefined behavior via out-of-bounds pointer access in stainless_ffmpeg stream accessors, potentially leading to crashes or code execution.

- **Severity:** Not scored
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Not stated
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 24 Apr 2025

## What is RUSTSEC-2025-0169?

RUSTSEC-2025-0169 is a memory corruption vulnerability in stainless_ffmpeg, published on 24 Apr 2025. 

### Official description

Affected versions of `stainless_ffmpeg` exposed several safe public methods on `FormatContext` that accepted a `stream_index` parameter and used it in unsafe pointer operations without checking whether the index was valid. These methods performed pointer arithmetic and dereferenced the resulting stream pointer. Safe callers could pass a negative or out-of-bounds `stream_index`, which could cause out-of-bounds pointer access and undefined behavior from safe Rust code.

The issue was fixed in version `0.6.0` by marking the affected stream accessor methods as `unsafe` and documenting that callers must ensure `stream_index` is a valid stream index.

## Which versions are affected by RUSTSEC-2025-0169?

1 open source package ship an affected version, including stainless_ffmpeg.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `stainless_ffmpeg` | crates.io | From 0.0.0-0 | 0.6.0 |

## How do I fix RUSTSEC-2025-0169?

Upgrade stainless_ffmpeg to 0.6.0 or later.

## Is RUSTSEC-2025-0169 being exploited?

There is no known exploitation of RUSTSEC-2025-0169 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for RUSTSEC-2025-0169 and fix it if it is affected.

What it is: RUSTSEC-2025-0169 is a memory corruption vulnerability in stainless_ffmpeg, published on 24 Apr 2025. 
Exploitation: There is no known exploitation of RUSTSEC-2025-0169 in the wild and no public exploit code.

Affected packages and fixed versions:
- stainless_ffmpeg (crates.io): affected from 0.0.0-0; fixed in 0.6.0

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/RUSTSEC-2025-0169/ (Markdown: https://insights.sbomify.com/RUSTSEC-2025-0169/index.md)
```

## Sources

- OSV: https://osv.dev/vulnerability/RUSTSEC-2025-0169

---
From sbomify Insights: https://insights.sbomify.com/RUSTSEC-2025-0169/
Summaries are generated and may contain mistakes; the official description above is the record.