Affected: pyload

pyload is an open-source Download Manager written in pure Python. An unsafe JavaScript evaluation vulnerability in pyLoad’s CAPTCHA processing code allows unauthenticated remote attackers to execute arbitrary code in the client browser and potentially the backend server. Exploitation requires no user interaction or authentication and can result in session hijacking, credential theft, and full system remote code execution. Commit 909e5c97885237530d1264cfceb5555870eb9546, the patch for the issue, is included in version 0.5.0b3.dev89.

Affected: PyPI: pyload-ng

#### Summary An unsafe JavaScript evaluation vulnerability in pyLoad’s CAPTCHA processing code allows **unauthenticated remote attackers** to execute **arbitrary code** in the client browser and potentially the backend server. Exploitation requires no user interaction or authentication and can result in session hijacking, credential theft, and full system rce.

#### Details The vulnerable code resides in ```javascript function onCaptchaResult(result) { eval(result); // Direct execution of attacker-controlled input } ```

* The `onCaptchaResult()` function directly passes CAPTCHA results (sent from the user) into `eval()` * No sanitization or validation is performed on this input * A malicious CAPTCHA result can include JavaScript such as `fetch()` or `child_process.exec()` in environments using NodeJS * Attackers can fully hijack sessions and pivot to remote code execution on the server if the environment allows it

### Reproduction Methods 1. **Official Source Installation**: ```bash git clone https://github.com/pyload/pyload cd pyload git checkout 0.4.20 python -m pip install -e . pyload --userdir=/tmp/pyload ```

2. **Virtual Environment**: ```bash python -m venv pyload-env source pyload-env/bin/activate pip install pyload==0.4.20 pyload ```

## CAPTCHA Endpoint Verification

**Technical Clarification**: 1. The vulnerable endpoint is actually: ``` /interactive/captcha ```

2. Complete PoC Request: ```http POST /interactive/captcha HTTP/1.1 Host: local…