# CVE-2024-32481: vyper's range(start, start + N) reverts for negative numbers

Source: https://junglewise.ai/threats/cve-2024-32481-vyper-s-range-start-start-n-reverts-for-negative-numbers  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2024-04-25  
License: CC BY 4.0 with a link back

CVE-2024-32481 · Severity: low · CVSS 3.1 · Published 2024-04-25

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.

Technologies: [vyper (PyPI)](https://junglewise.ai/threats/technologies/vyper). Vendors: [PyPI](https://junglewise.ai/threats/vendors/pypi).

## Quick answers

**Is CVE-2024-32481 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2024-32481 being exploited in the wild.

**How severe is CVE-2024-32481?** Low severity, with a CVSS score of 3.1, published 25 April 2024.

**Which products and versions are affected?** vyper (PyPI) ECOSYSTEM:introduced=0.3.8,fixed=0.4.0, ECOSYSTEM:introduced=0.3.8,fixed=0.4.0b1.

**Is there a fix for CVE-2024-32481?** Yes. vyper (PyPI): upgrade to 0.4.0, 0.4.0b1 or later. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**Am I affected by CVE-2024-32481?** Check whether you run vyper (PyPI) at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## How to fix

- vyper (PyPI): upgrade to 0.4.0, 0.4.0b1 or later

  ```sh
  pip install "vyper>=0.4.0b1"
  ```


## Affected products

- vyper (PyPI) ECOSYSTEM:introduced=0.3.8,fixed=0.4.0, ECOSYSTEM:introduced=0.3.8,fixed=0.4.0b1

## Identifiers

- CVE-2024-32481
- GHSA-ppx5-q359-pvwj
- PYSEC-2024-246

## Related threats

- [Vyper memory corruption in nested function calls and tuples](https://junglewise.ai/threats/vyper-memory-corruption-using-function-calls-within-tuples-nested-calls-c0689acb)
- [Vyper stack corruption in complex type argument passing](https://junglewise.ai/threats/vyper-call-stack-corruption-when-passing-complex-type-containing-non-3deb0c30)
- [Vyper return statement in nested for loops causes revert](https://junglewise.ai/threats/vyper-return-inside-for-loop-more-than-1-level-deep-ee8a193d)
- [PYSEC-2026-2028 - Vyper's `slice()` may elide side-effects when output length is 0](https://junglewise.ai/threats/cve-2025-47774-vyper-s-slice-may-elide-side-effects-when-output-length-is-0)
- [PYSEC-2026-2029 - Vyper's `concat()` builtin may elide side-effects for zero-length arguments](https://junglewise.ai/threats/cve-2025-47285-vyper-s-concat-builtin-may-elide-side-effects-for-zero-length)