ERC777 tokens allow arbitrary callbacks via hooks that are called during token transfers. Malicious contract addresses may cause reentrancy on such callbacks if reentrancy guards are not used. (see here)
- ERC777 Token Standard
- Callbacks -> Reentrancy
- Hooks -> Reentrancy
- C1 -> ERC777 -> Hook -> C1
- CEI Pattern
- Reentrancy Guards