Critical Remote Code Execution Vulnerability in css-vvgsze-polyfill Package
Summary
MAL-2026-17577: Malicious code in css-vvgsze-polyfill (npm). Affects css-vvgsze-polyfill versions 1.0.0. No fix is published. How to fix ↓
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Background
The css-vvgsze-polyfill package is an npm module designed to provide CSS polyfill functionalities. It aims to enhance compatibility across different browsers by mimicking certain CSS features. However, this package has been found to contain malicious code that compromises the security of the systems using it, particularly targeting CI/build environments.
Vulnerability Detail
The vulnerability originates from a malicious script embedded in the thunderboltRegistry.js file of the css-vvgsze-polyfill package. This script executes commands that leak sensitive information such as environment variables, which may include cloud credentials and API keys, to an external server. Additionally, it fetches and executes a remote JavaScript payload, allowing for full remote code execution on the host system. This poses a significant risk to any application using this package, especially in production environments.
How To Fix
This package is malicious. Remove it and rotate any credentials it could have accessed.
npm uninstall css-vvgsze-polyfillIf it arrived as a transitive dependency, remove the package that pulled it in, then reinstall.
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Workaround
As a temporary workaround, you can remove the css-vvgsze-polyfill package from your project dependencies and replace it with a trusted alternative that provides similar CSS polyfill functionalities. Additionally, ensure that your CI/build environments are secured and monitored for unauthorized access.
Conclusion
The css-vvgsze-polyfill package contains a critical vulnerability that can lead to remote code execution and sensitive data leakage. It is essential to remove this package from your project and monitor your systems for any potential threats. Utilizing tools like Vulert can help in identifying and managing such vulnerabilities effectively.
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FAQ
css-vvgsze-polyfill is an npm package that provides CSS polyfill functionalities to enhance browser compatibility.
The vulnerability allows attackers to execute remote code on your system and leak sensitive information, which can lead to severe security breaches.
You should immediately remove the css-vvgsze-polyfill package from your project and monitor your environment for any suspicious activity.
Yes, you can use Vulert to monitor and alert for open-source vulnerabilities in your software. Visit Vulert Scanner to check your application without any signup.
Failure to address this vulnerability can result in unauthorized access to your systems, data breaches, and potential loss of sensitive information.
