CVE-2025-4727 Meteor livedata_server.js Object.assign redos
Remote attackers can cause denial of service in Meteor applications via inefficient regular expression complexity in the livedata server.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- None listed
What is CVE-2025-4727?
CVE-2025-4727 is a medium-severity denial of service vulnerability in Meteor, published on 15 May 2025. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official 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.
Which versions are affected by CVE-2025-4727?
2 open source packages ship an affected version, including meteor. It affects 1 product.
| Package | Affected | Fixed in |
|---|---|---|
meteor npm | All versions to 3.2.1 | None |
meteor npm | All versions to 3.2.1 | None |
Products include Meteor Meteor.
How do I fix CVE-2025-4727?
No fix has been published for CVE-2025-4727 yet. Limit exposure of the affected software until one is available.
Upgrade, then put limits on request size, rate and nesting depth so one client cannot exhaust the service. More about Denial of service.
Is CVE-2025-4727 being exploited?
It is not confirmed as exploited in the wild, but public exploit code for CVE-2025-4727 exists.
Sources
Also known as GHSA-j3v9-6gc7-vf5f.