GHSA-j2x6-9323-fp7h

Integer bounds error in Vyper

### Impact in the following code, the return of `<iface>.returns_int128()` is not validated to fall within the bounds of `int128`. as of v0.3.0, `<iface>.returns_int128()` is validated in simple expressions, but not complex expressions. ```vyper interface iface: def returns_int128() -> int128: view def returns_Bytes33() -> Bytes[33]: view x: iface @external def call_out(): x: int128 = self.x.returns_int128() # affected, <0.3.0 y: uint256 = convert(self.x.returns_int128(), uint256) # affected, <0.3.2 z: Bytes[33] = concat(self.x.returns_Bytes33(), b"") # affected >= 0.3.0, <0.3.2 ``` ### Patches 0.3.2 (as of https://github.com/vyperlang/vyper/commit/049dbdc647b2ce838fae7c188e6bb09cf16e470b) ### Workarounds Break up operations involving external calls into multiple statements. For instance, instead of the example above, use ``` x: int128 = self.x.returns_int128() y: uint256 = convert(x, uint256) ```