What’s Vulnerable › Vulnerabilities

CVE-2023-42441: Vyper has incorrect re-entrancy lock when key is empty string

• Severity: medium (CVSS 5.3 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.5% probability of exploitation in the next 30 days
• Public exploit or detection template: yes
• Published: 2023-09-18 · updated 2026-06-17
• Weakness: CWE-833

Description

Vyper is a Pythonic Smart Contract Language for the Ethereum Virtual Machine (EVM). Starting in version 0.2.9 and prior to version 0.3.10, locks of the type `@nonreentrant("")` or `@nonreentrant('')` do not produce reentrancy checks at runtime. This issue is fixed in version 0.3.10. As a workaround, ensure the lock name is a non-empty string.

Affected products

• vyperlang vyper: from 0.2.9 before 0.3.10 — fixed in 0.3.10

How to fix

Upgrade to a fixed version: vyperlang vyper 0.3.10. Check the vendor advisory for mitigations.

References

• https://github.com/vyperlang/vyper/commit/0b740280c1e3c5528a20d47b29831948ddcc6d83
• https://github.com/vyperlang/vyper/pull/3605
• https://github.com/vyperlang/vyper/security/advisories/GHSA-3hg2-r75x-g69m
• https://github.com/vyperlang/vyper/commit/0b740280c1e3c5528a20d47b29831948ddcc6d83
• https://github.com/vyperlang/vyper/pull/3605
• https://github.com/vyperlang/vyper/security/advisories/GHSA-3hg2-r75x-g69m

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