---
tags:
  - security
  - proof-of-concept
  - protobuf
license: mit
---

# Protocol Buffers FileDescriptorProto option_dependency string materialization DoS PoC

This repository contains a benign security research PoC for a `.pb` artifact
that drives repeated-string materialization during
`descriptor_pb2.FileDescriptorProto.ParseFromString(...)`.

Files:

- `control_one_dependency.pb`
- `malicious_option_dependency_5000000.pb`
- `reproduce.py`

Observed behavior:

- control artifact:
  - parses successfully with one `dependency`
- malicious artifact:
  - parses successfully with `5,000,000` empty `option_dependency` strings
  - materially increases peak RSS during normal parse

Tested runtime:

```bash
python3 -m pip install protobuf==7.35.1
```