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

# MessagePack array32 repeated-empty-string materialization DoS PoC

This repository contains a benign security research PoC for a `.msgpack`
artifact that drives large in-memory materialization during
`msgpack.unpackb(..., raw=False)`.

Files:

- `control_bin32_same_size.msgpack`
- `malicious_array32_empty_strings_20000000.msgpack`
- `reproduce.py`

Observed behavior:

- control artifact:
  - parses successfully as one `bytes` object
- malicious artifact:
  - same size as control
  - parses successfully as a list of `20,000,000` empty strings
  - materially increases peak RSS during normal unpack

Reproduction:

```bash
python3 build_poc.py
python3 reproduce.py
```