cve/2024/CVE-2024-32481.md

### [CVE-2024-32481](https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2024-32481)
![](https://img.shields.io/static/v1?label=Product&message=vyper&color=blue)
![](https://img.shields.io/static/v1?label=Version&message=%3D%20%3E%3D%200.3.8%2C%20%3C%200.4.0b1%20&color=brighgreen)
![](https://img.shields.io/static/v1?label=Vulnerability&message=CWE-681%3A%20Incorrect%20Conversion%20between%20Numeric%20Types&color=brighgreen)

### Description

Vyper is a pythonic Smart Contract Language for the Ethereum virtual machine. Starting in version 0.3.8 and prior to version 0.4.0b1, when looping over a `range` of the form `range(start, start + N)`, if `start` is negative, the execution will always revert. This issue is caused by an incorrect assertion inserted by the code generation of the range `stmt.parse_For_range()`. The issue arises when `start` is signed, instead of using `sle`, `le` is used and `start` is interpreted as an unsigned integer for the comparison. If it is a negative number, its 255th bit is set to `1` and is hence interpreted as a very large unsigned integer making the assertion always fail. Any contract having a `range(start, start + N)` where `start` is a signed integer with the possibility for `start` to be negative is affected. If a call goes through the loop while supplying a negative `start` the execution will revert. Version 0.4.0b1 fixes the issue.

### POC

#### Reference
- https://github.com/vyperlang/vyper/security/advisories/GHSA-ppx5-q359-pvwj

#### Github
- https://github.com/fkie-cad/nvd-json-data-feeds