CVE-2023-32675: Nonpayable default functions are sometimes payable in vyper

Severity: medium (CVSS 5.3 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.6% probability of exploitation in the next 30 days
Public exploit or detection template: yes
Published: 2023-05-19 · updated 2026-06-17
Weakness: CWE-670

Description

Vyper is a pythonic Smart Contract Language for the ethereum virtual machine. In contracts with more than one regular nonpayable function, it is possible to send funds to the default function, even if the default function is marked `nonpayable`. This applies to contracts compiled with vyper versions prior to 0.3.8. This issue was fixed by the removal of the global `calldatasize` check in commit `02339dfda`. Users are advised to upgrade to version 0.3.8. Users unable to upgrade should avoid use of nonpayable default functions.

Affected products

vyperlang vyper: before 0.3.8 — fixed in 0.3.8

How to fix

Upgrade to a fixed version: vyperlang vyper 0.3.8. Check the vendor advisory for mitigations.

References

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