The Front End Users plugin for WordPress is vulnerable to arbitrary file uploads due to missing file type validation in the file uploads field of the registration form in all versions up to, and including, 3.2.32. This makes it possible for unauthenticated attackers to upload arbitrary files on the affected site's server which may make remote code execution possible.

Ethernaut

The Ethernaut is a Web3/Solidity based wargame played in the Ethereum Virtual Machine. Each level is a smart contract that needs to be 'hacked'. The game is 100% open source and all levels are contributions made by other players.