---
title: "CVE-2024-24561: Vyper's bounds check on built-in `slice()` function can be overflowed"
url: https://erroneo.us/security/cve/CVE-2024-24561/
description: "CVE-2024-24561 (vyper (PyPI)): Vyper is a pythonic Smart Contract Language for the ethereum virtual machine. In versions 0.3.10 and earlier, the bounds…"
type: vulnerability-record
section: "Security Digest"
date_published: 2024-02-01
date_modified: 2025-06-17
publisher: erroneo.us
author: erroneo.us Security Desk
cve: "CVE-2024-24561"
kev: false
cvss: 9.8
epss: 0.00902
license: All rights reserved. Quote with attribution and a link.
---

# CVE-2024-24561: Vyper's bounds check on built-in `slice()` function can be overflowed

**Signal:** Critical and remotely reachable. No known exploitation yet, but it is network-reachable without credentials. (Computed from CISA KEV, EPSS and CVSS; not an editorial verdict.)

## Should you act?

- Not in CISA KEV , but CISA’s SSVC assessment records a public proof-of-concept, so attack code exists.
- EPSS 0.9% , percentile 59: FIRST’s model estimates a 0.9% chance of exploitation activity in the next 30 days, higher than 59% of all scored CVEs (moderate). EPSS is a probability, not a verdict.
- Remotely reachable with no login and no user interaction. If the vulnerable service is exposed to the internet, prioritize it.
- Only applies if your dependency tree includes vyper (PyPI) <= 0.3.10, fixed in 0.4.0 . Check your lockfile, including transitive dependencies.

## What it is

Vyper is a pythonic Smart Contract Language for the ethereum virtual machine. In versions 0.3.10 and earlier, the bounds check for slices does not account for the ability for start + length to overflow when the values aren't literals. If a slice() function uses a non-literal argument for the start or length variable, this creates the ability for an attacker to overflow the bounds check. This issue can be used to do OOB access to storage, memory or calldata addresses. It can also be used to corrupt the length slot of the respective array.

## Affected packages

- PyPI `vyper` <= 0.3.10 → fixed: 0.4.0

## Affected products (CVE record)

- vyperlang vyper: <= 0.3.10

## Severity

- GitHub_M CVSS 3.1: 9.8 `CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H`
- GitHub CVSS 3.1: 9.8 `CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H`

## Exploitation

- CISA KEV: not listed (no confirmed in-the-wild exploitation known to CISA).
- CISA SSVC assessment: exploitation poc , automatable yes , technical impact total .
- FIRST EPSS (model of 2026-10-21): 0.90% probability of exploitation activity in the next 30 days; percentile 59.

## Sources

- [GitHub Advisory GHSA-9x7f-gwxq-6f2c](https://github.com/advisories/GHSA-9x7f-gwxq-6f2c)
- [CVE.org record CVE-2024-24561](https://www.cve.org/CVERecord?id=CVE-2024-24561)
- [NVD entry CVE-2024-24561](https://nvd.nist.gov/vuln/detail/CVE-2024-24561)
- [github.com](https://github.com/vyperlang/vyper/security/advisories/GHSA-9x7f-gwxq-6f2c)
- [github.com](https://github.com/vyperlang/vyper/issues/3756)
- [github.com](https://github.com/vyperlang/vyper/blob/b01cd686aa567b32498fefd76bd96b0597c6f099/vyper/builtins/functions.py#L404-L457)
- [github.com](https://github.com/pypa/advisory-database/tree/main/vulns/vyper/PYSEC-2024-149.yaml)

---
Source page: https://erroneo.us/security/cve/CVE-2024-24561/ · Security Digest: https://erroneo.us/security/ · More: https://erroneo.us/llms.txt