{"id":"CVE-2023-39363","aliases":["GHSA-5824-cm3x-3c38","PYSEC-2023-142"],"url":"https://o3.security/vulnerability/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.","published":"2023-08-07T18:40:25.615Z","modified":"2026-07-15T01:49:06.894380597Z","cvss":null,"epss":null,"cisaKev":null,"exploitsKnown":3,"affectedPackages":[{"ecosystem":"PyPI","name":"vyper","fixedVersion":"0.3.1"}],"fix":{"url":"https://github.com/vyperlang/vyper/pull/2439","label":"vyperlang/vyper#2439"},"references":[{"type":"WEB","url":"https://hackmd.io/@LlamaRisk/BJzSKHNjn"},{"type":"WEB","url":"https://hackmd.io/@vyperlang/HJUgNMhs2"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2023/39xxx/CVE-2023-39363.json"},{"type":"ADVISORY","url":"https://github.com/vyperlang/vyper/security/advisories/GHSA-5824-cm3x-3c38"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2023-39363"},{"type":"FIX","url":"https://github.com/vyperlang/vyper/pull/2439"},{"type":"FIX","url":"https://github.com/vyperlang/vyper/pull/2514"}],"provenance":{"sources":["OSV.dev","FIRST.org (EPSS)"],"lastVerified":"2026-07-15T01:49:06.894380597Z"}}