Vyper is a Pythonic Smart Contract Language for the Ethereum Virtual Machine (EVM). In versions 0.2.15, 0.2.16 and 0.3.0, named re-entrancy locks are allocated incorrectly. Each function using a named re-entrancy lock gets a unique lock regardless of the key, allowing cross-function re-entrancy in contracts compiled with the susceptible versions. A specific set of conditions is required to result in misbehavior of affected contracts, specifically: a `.vy` contract compiled with `vyper` versions `0.2.15`, `0.2.16`, or `0.3.0`; a primary function that utilizes the `@nonreentrant` decorator with a specific `key` and does not strictly follow the check-effects-interaction pattern (i.e. contains an external call to an untrusted party before storage updates); and a secondary function that utilizes the same `key` and would be affected by the improper state caused by the primary function. Version 0.3.1 contains a fix for this issue.
The product performs an authorization check when an actor attempts to access a resource or perform an action, but it does not correctly perform the check.
| Link | Tags |
|---|---|
| https://github.com/vyperlang/vyper/security/advisories/GHSA-5824-cm3x-3c38 | patch third party advisory exploit |
| https://github.com/vyperlang/vyper/pull/2439 | patch |
| https://github.com/vyperlang/vyper/pull/2514 | patch |
| https://hackmd.io/@LlamaRisk/BJzSKHNjn | third party advisory exploit |
| https://hackmd.io/@vyperlang/HJUgNMhs2 | third party advisory exploit |