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

# Protocol Buffers FieldMask paths materialization DoS PoC

This repository contains a benign security research PoC for a `.pb` artifact
that drives repeated-string materialization during
`field_mask_pb2.FieldMask.ParseFromString(...)`.

Files:

- `control_one_path.pb`
- `malicious_paths_5000000.pb`
- `reproduce.py`

Observed behavior:

- control artifact:
  - parses successfully with one `paths` entry
- malicious artifact:
  - parses successfully with `5,000,000` `paths` entries
  - materially increases peak RSS during normal parse

Tested runtime:

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