CVE-2023-39363

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CVE-2023-39363

Summary: Vyper incorrectly allocated named re-entrancy locks

Details: 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.

References: https://hackmd.io/@LlamaRisk/BJzSKHNjn, https://hackmd.io/@vyperlang/HJUgNMhs2, https://github.com/CVEProject/cvelistV5/tree/main/cves/2023/39xxx/CVE-2023-39363.json, https://github.com/vyperlang/vyper/security/advisories/GHSA-5824-cm3x-3c38, https://nvd.nist.gov/vuln/detail/CVE-2023-39363, https://github.com/vyperlang/vyper/pull/2439, https://github.com/vyperlang/vyper/pull/2514