GHSA-vq8p-m3wm-gv5f
pyLoad: Lack of Input Size Validation Leads to Denial of Service (DoS) and Process Termination
Packages
Details
As written in the advisory (Markdown source, shown as plain text).
## Description:
The API `rpc` function in `api_blueprint.py` handles `multipart/form-data` uploads by reading the whole content of the uploaded file into memory with `file.read()`. This occurs before the data is sent to the underlying function. Since there is no size limit set at this point, a large file upload can exhaust the server's available memory which led to process termination.
## VulnerableCode & Path:
https://github.com/pyload/pyload/blob/8e447958b8a66c5899775e725a8b90bce6643004/src/pyload/webui/app/blueprints/api_blueprint.py#L73
## Steps to Reproduce:
1. Log in to pyLoad (or use an API key, here i used api to communicate).
2. Prepare a large file (e.g., 10GB) .
```bash
truncate -s 10G large_file.bin
```
3. Send a multipart request to an API function that accepts a file, such as `check_online_status_container`:
```bash
curl -X POST "http://localhost:8000/api/rpc" \
-H "X-API-Key: YOUR_API_KEY" \
-F "func=check_online_status_container" \
-F "container=@large_file.bin"
```
4. Monitor the server's memory usage. The process will attempt to allocate memory for the entire file and last the process will be killed by the kernel.
<img width="1902" height="610" alt="dos-process-kill-poc" src="https://github.com/user-attachments/assets/2b9bfd0f-5b9f-48dd-983f-f97dfcc358cc" />
## Impact
- **Denial of Service (DoS)**: The pyLoad process will be killed by the Operating System's Out-Of-Memory (OOM) killer, or the entire system may become unresponsive due to swap thrashing or memory exhaustion.
- **Service Instability**: Any active downloads or tasks will be interrupted.
## Mitigations
- **Implement File Size Limits**: Enforce a maximum size for uploaded files in the web server configuration (e.g., Nginx `client_max_body_size`).
References
External links from the advisory. They lead to third-party sites.