Vulnerabilities > CVE-2022-29255 - Always-Incorrect Control Flow Implementation vulnerability in Vyperlang Vyper
Attack vector
NETWORK Attack complexity
LOW Privileges required
NONE Confidentiality impact
NONE Integrity impact
HIGH Availability impact
NONE Summary
Vyper is a Pythonic Smart Contract Language for the ethereum virtual machine. In versions prior to 0.3.4 when a calling an external contract with no return value, the contract address (including side effects) could be evaluated twice. This may result in incorrect outcomes for contracts. This issue has been addressed in v0.3.4.