CVE-2026-114663

Vyper 0.4.0b1 through 0.5.0b1 miscompiles unfoldable constants and omitted default arguments from imported modules, because parse Name resolves their names in the using function's scope rather than at declaration. When a contract's parameter, local, or loop variable shares such a name, attacker-influenced input can replace the intended value, including out-of-range values for narrow types such as uint8, corrupting validation or accounting logic.