CVE-2024-32648

### Summary Prior to v0.3.0, `__default__()` functions did not respect the `@nonreentrancy` decorator and the lock was not emitted. This is a known bug and was already visible in the issue tracker (https://github.com/vyperlang/vyper/issues/2455), but it is being re-issued as an advisory so that tools relying on the advisory publication list can incorporate it into their searches. A contract search was additionally performed and no vulnerable contracts were found in production. ### PoC ```vyper @external @payable @nonreentrant("default") def __default__(): pass ``` after codegen: ``` [seq, [if, [lt, calldatasize, 4], [goto, fallback]], [mstore, 28, [calldataload, 0]], [with, _func_sig, [mload, 0], seq], [seq_unchecked, [label, fallback], [seq, pass, # Line 5 pass, pass, # Line 4 stop]]], ``` ### Impact No vulnerable production contracts were found. Additionally, using a lock on a `default` function is a very sparsely used pattern. As such, the impact is `low`.

Vyper is a pythonic Smart Contract Language for the Ethereum virtual machine. Prior to version 0.3.0, default functions don't respect nonreentrancy keys and the lock isn't emitted. No vulnerable production contracts were found. Additionally, using a lock on a `default` function is a very sparsely used pattern. As such, the impact is low. Version 0.3.0 contains a patch for the issue.