---
id: "CVE-2020-37287"
kind: "vulnerability"
aliases: ["CVE-2020-37287"]
title: "Vyper: call stack corruption garbles arrays and structs passed to functions"
severity: "high"
cvss: 8.2
epss: 0.00251
exploited: false
status: "open"
category: "package"
products: []
ecosystems: []
tags: ["ethereum", "package", "smart-contracts", "vyper"]
not_affected_if: ["base-type-arguments-only", "vyper-0.2.6-or-later"]
published_at: "2026-10-21T01:17:18+00:00"
first_seen_at: "2026-10-23T21:57:27+00:00"
updated_at: "2026-10-25T03:03:53+00:00"
sources: [{"source": "nvd", "url": "https://nvd.nist.gov/vuln/detail/CVE-2020-37287", "first_seen_at": "2026-10-23T21:57:27+00:00"}, {"source": "epss", "url": "https://api.first.org/data/v1/epss?cve=CVE-2020-37287", "first_seen_at": "2026-10-24T13:15:55+00:00"}]
---

# Vyper: call stack corruption garbles arrays and structs passed to functions

Vyper versions before 0.2.6 corrupt the call stack when multi-dimensional arrays or structs are passed as arguments, so functions receive wrong values. An attacker who can influence those inputs can make a contract act on incorrect data.

_Summary, check and fix written by a model from the sources; labelled as such._

## How to check

- Run `vyper --version` and check whether it is below `0.2.6`
- Search contract source and build config for pinned Vyper versions below `0.2.6`

## Fix

- Upgrade Vyper to `0.2.6` or later and recompile contracts
- Re-test contract functions that take arrays or structs as arguments

## Timeline

- 2026-10-23T21:57:27+00:00 nvd https://nvd.nist.gov/vuln/detail/CVE-2020-37287
- 2026-10-24T13:15:55+00:00 epss https://api.first.org/data/v1/epss?cve=CVE-2020-37287

## From the sources

Vyper before 0.2.6 contains a call stack corruption vulnerability that causes incorrect function outputs when complex types with non-base members are passed as arguments. Contracts passing multi-dimensional arrays or structs to internal or external functions receive corrupted values because the compiler assumed each subtype size is 32.

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_Free to read at a human pace. An API with keys and an MCP server are in preparation; early access: hello@infrastack.ai_