CVE-2025-4727 — meteor
Fix: meteor/meteor@f7ea681CVE-2025-4727 is a Uncontrolled Resource Consumption vulnerability in meteor. No vendor fix is recorded yet; mitigation options are listed below.
Meteor livedata_server.js Object.assign redos
Exploitation Status
Proof-of-concept exploit code exists
- CISA’s SSVC triage found public proof-of-concept exploit code for this CVE, though no confirmed active exploitation.
Exploitation and automatability from CISA’s SSVC triage for CVE-2025-4727.
EPSS Exploitation Probability
EPSS (Exploit Prediction Scoring System) is a daily probability model maintained by FIRST.org. It estimates the likelihood a CVE will be exploited in production environments within the next 30 days, derived from real-world threat intelligence signals.
Real-World Exposure
How broadly this vulnerability is actually deployed: weekly install volume shows current usage, and reverse-dependency count shows how many other packages break if it stays unpatched.
meteornpmDescription
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.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 📦npm | meteor | all versions | No fix |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for meteor, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Remediation status
No patched version of meteor has shipped for CVE-2025-4727 yet. Where your build allows, override or pin the dependency away from the vulnerable range, and apply any maintainer-recommended mitigation.
Mitigate without a patch
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.
How O3 protects you
O3 Security's impact-aware SCA analyses which vulnerable code paths your application actually calls, so a match like CVE-2025-4727 can be triaged on real exposure rather than presence alone.
Tailored to CVE-2025-4727. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Frequently Asked Questions
Is CVE-2025-4727 in your dependencies?
O3 Security finds CVE-2025-4727 across npm dependencies, including transitive ones, and its impact-aware SCA ranks findings by whether your code actually calls the vulnerable path.