Malicious Code Injection in mass_mouse_z3n Package: A Threat to npm Ecosystem
Summary
MAL-2025-88317: Malicious code in mass_mouse_z3n (npm). Affected versions are not published. No fix is published. How to fix ↓
Check if this vulnerability affects your application
Upload a manifest or SBOM and we'll show whether you're affected, plus every other risky package in the same scan.
No signup required · Results in about 60 seconds
Background
The mass_mouse_z3n package is part of the npm ecosystem, which is widely used for JavaScript package management. It is often utilized in various projects to facilitate the integration of third-party libraries. However, this package has been identified as part of a malicious campaign that aims to exploit the npm registry by flooding it with derivative packages that inflate developer reputation scores for token rewards.
Vulnerability Detail
The vulnerability in the mass_mouse_z3n package stems from its association with a malicious campaign that modifies the package.json file to remove private flags, alters version numbers, and generates random package names. This behavior is designed to continuously republish variants, polluting the npm registry and potentially compromising the integrity of applications that depend on these packages. The malicious code is part of a broader scheme to manipulate the npm ecosystem for financial gain.
How To Fix
This package is malicious. Remove it and rotate any credentials it could have accessed.
npm uninstall mass_mouse_z3nIf it arrived as a transitive dependency, remove the package that pulled it in, then reinstall.
Tip — Not sure whether your app is affected? Vulert can check the versions your app actually runs. Scan free →
Workaround
As a temporary workaround, you can avoid using the mass_mouse_z3n package and replace it with a trusted alternative. Additionally, you can use the following command to uninstall the package: npm uninstall mass_mouse_z3n.
Conclusion
The mass_mouse_z3n package poses a significant threat to the npm ecosystem due to its malicious code that manipulates package metadata and floods the registry. It is essential for developers to be vigilant, remove affected packages, and utilize tools like Vulert to monitor their projects for vulnerabilities.
See every vulnerability recorded for mass_mouse_z3n →
FAQ
mass_mouse_z3n is an npm package that has been identified as part of a malicious campaign to manipulate the npm registry.
The vulnerability can lead to the introduction of malicious code in your project, potentially compromising its security and integrity.
You can use Vulert, which monitors and alerts for open-source vulnerabilities in real-time. Visit Vulert Scanner to check if your application is affected without requiring any signup.
You should uninstall the mass_mouse_z3n package immediately and monitor your project for any unusual behavior.
Yes, tools like Vulert can help monitor your dependencies for vulnerabilities using just the package-lock.json file.
