The Avatar exploit involves circumventing the strict whitelist and execution limitations of an eval function in a Pythong script that executes user input. The solution exploits the system by dynamically constructing Python expressions that conform to the whitelist but when evaluated, perform unintended actions like gaining shell access. The exploit achieves this by using Boolean operations and formatted strings to recreate numeric values and ASCII characters, allowing for the construction of complex expressions that execute OS commands, leading to a shell where the flag can be read directly from the system.
