Vyper is a Pythonic Smart Contract Language for the Ethereum Virtual Machine. In version 0.3.1 and prior, bytestrings can have dirty bytes in them, resulting in incorrect word-for-word comparisons. Even without dirty nonzero bytes, two bytestrings can compare to equal if one ends with `"\x00"` because there is no comparison of the length. This issue was fixed in version 0.3.2.
CWE-697 - Incorrect Comparison
The software compares two entities in a security-relevant context, but the comparison is incorrect, which may lead to resultant weaknesses.