{"cve":"CVE-2023-39363","nvd":{"published":"2023-08-07T19:15:11.873","modified":"2026-06-17T06:12:08.867","status":"Modified","description":"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.","cvss_v4":{"vector":"CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:H/VA:H/SC:N/SI:H/SA:H/E:A","score":9.1},"cvss_v3":{"version":"3.1","vector":"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:H/A:N","score":5.9},"cwes":["CWE-863"],"references":["https://github.com/vyperlang/vyper/pull/2439","https://github.com/vyperlang/vyper/pull/2514","https://github.com/vyperlang/vyper/security/advisories/GHSA-5824-cm3x-3c38","https://hackmd.io/@LlamaRisk/BJzSKHNjn","https://hackmd.io/@vyperlang/HJUgNMhs2"],"products":["vyperlang:vyper"],"source":"nvd","synced_at":"2026-10-19T21:38:35.729974749+00:00"},"epss":{"cve":"CVE-2023-39363","score":0.00821,"percentile":0.57311,"date":"2026-11-01"},"kev":null,"osv":[{"id":"GHSA-5824-cm3x-3c38","url":"https://osv.dev/vulnerability/GHSA-5824-cm3x-3c38","summary":"Vyper has incorrectly allocated named re-entrancy locks","modified":"2026-09-10T03:49:57.451549676Z","packages":[{"ecosystem":"PyPI","name":"vyper","purl":"pkg:pypi/vyper","ranges":[">=0.2.15 <0.3.1"],"fixed":["0.3.1"]}]},{"id":"PYSEC-2023-142","url":"https://osv.dev/vulnerability/PYSEC-2023-142","summary":"","modified":"2025-10-09T08:26:23.283831Z","packages":[{"ecosystem":"PyPI","name":"vyper","purl":"pkg:pypi/vyper","ranges":["all versions"],"fixed":[]}]}],"attribution":["This product uses the NVD API but is not endorsed or certified by the NVD.","EPSS scores: FIRST Exploit Prediction Scoring System, https://www.first.org/epss","Known exploited vulnerabilities: CISA Known Exploited Vulnerabilities Catalog, https://www.cisa.gov/known-exploited-vulnerabilities-catalog","Package advisories: OSV (https://osv.dev), from the GitHub Advisory Database, PyPA, Go, RustSec and other ecosystem databases, under CC-BY 4.0 or CC0","CVE records: the CVE Program's CVE List (https://www.cve.org), under its terms of use (https://www.cve.org/Legal/TermsOfUse). CVE is a registered trademark of The MITRE Corporation; this product is not affiliated with the CVE Program."]}