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.
CVE-2023-39363
This medium-severity CVE scores 5.9 under NVD CVSS v3. EPSS exploit probability: 0.8% (55th percentile of EPSS-scored CVEs). GitHub Security Advisory data not yet ingested — confidence will rise once GHSA publishes (typical lag: hours to days for open-source ecosystem CVEs; never for infrastructure-only CVEs).
- Lower severity and no public exploit yet
A fix is available — apply it.
- CVSS v3
- 5.9
- EG Score
- 5.9MEDIUMmedium confidence
- EG Risk
- 27EG Risk 27/100CISA SSVC
EG Risk is EchelonGraph's 0–100 priority score: it fuses intrinsic severity with real-world exploitation and automatability so you can rank equal-severity CVEs and fix the most dangerous first. Higher = act sooner. Distinct from the 0–10 EG Score (severity).
How it’s computedSeverity59% × 45%Exploitation1% × 40%Automatability0% × 15%CISA SSVC: Track at every mission impact level.Action: A fix is available. Apply it within your standard update timelines. - EPSS PROB
- 0.8%
- EPSS %ILE
- 56th
- KEV
- Not listed
CISA SSVCTrack at every mission impact level.
A fix is available. Apply it within your standard update timelines.
Exploitation none (CISA Vulnrichment) · Automatable no (CISA Vulnrichment) · Technical impact partial (CISA Vulnrichment). Mission impact is CISA's Mission & Well-being decision point, and only you can judge it: high means the affected system is essential to your organisation's mission, or its compromise could cause irreversible harm to people. CISA's decision table
Published
August 7, 2023
Last Modified
November 21, 2024
References (10)
- security-advisories@githubhttps://github.com/vyperlang/vyper/pull/2439
- security-advisories@githubhttps://github.com/vyperlang/vyper/pull/2514
- security-advisories@githubhttps://github.com/vyperlang/vyper/security/advisories/GHSA-5824-cm3x-3c38
- security-advisories@githubhttps://hackmd.io/@LlamaRisk/BJzSKHNjn
- security-advisories@githubhttps://hackmd.io/@vyperlang/HJUgNMhs2
- af854a3a-2127-422b-91ae-364da2661108https://github.com/vyperlang/vyper/pull/2439
- af854a3a-2127-422b-91ae-364da2661108https://github.com/vyperlang/vyper/pull/2514
- af854a3a-2127-422b-91ae-364da2661108https://github.com/vyperlang/vyper/security/advisories/GHSA-5824-cm3x-3c38
- af854a3a-2127-422b-91ae-364da2661108https://hackmd.io/@LlamaRisk/BJzSKHNjn
- af854a3a-2127-422b-91ae-364da2661108https://hackmd.io/@vyperlang/HJUgNMhs2
Affected Packages
(1 across 1 ecosystem)
PyPI(1)
| Package | Vulnerable range | Fix by version range | Dependents |
|---|---|---|---|
| vyper | 0.1.0b1 ... 0.4.3rc1 (74 versions) |
| — |
Weakness Classification(1)
MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.
Data Freshness Timeline
(refreshed 8× in last 7d / 33× in last 30d)
Each row is a source pipeline that fetched or updated this CVE on that date, with what changed. For example, "NVD update" means NVD published or revised its analysis for this CVE; "MITRE cvelistV5" means we ingested or refreshed it from the CNA feed. Most recent first.
Showing the most recent 100 of 200 total refreshes for this CVE.
- 2026-10-09 20:05 UTCEPSS rescore
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Related CVEs(same product + same CWE)
Same product
10 shownPyPI:vyper
Frequently asked(5)
What is CVE-2023-39363?
When was CVE-2023-39363 disclosed?
Is CVE-2023-39363 actively exploited?
What is the CVSS score of CVE-2023-39363?
How do I remediate CVE-2023-39363?
Dependency Blast Radius
See which npm, PyPI, Go, and Maven packages are affected by CVE-2023-39363
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