Critical Malicious Code Vulnerability in css-dwsawd-polyfill Package
Summary
MAL-2026-17550: Malicious code in css-dwsawd-polyfill (npm). Affects css-dwsawd-polyfill versions 1.0.0. No fix is published. How to fix ↓
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Background
The css-dwsawd-polyfill package is an npm module that mimics a legitimate Wix thunderbolt polyfill. It is designed to provide compatibility for certain functionalities within web applications. However, this package has been identified as containing malicious code that can execute unauthorized commands on the host system, posing a significant security risk.
Vulnerability Detail
The vulnerability originates from the package's malicious code, which is embedded in the thunderboltRegistry.js file. Upon requiring this module, it executes shell commands to gather system information and sends this data to an external server via an HTTP request. This behavior can lead to unauthorized data exposure and potential system compromise. The malicious actions include executing commands like 'id', 'whoami', and 'ifconfig', which can reveal sensitive information about the host environment.
How To Fix
This package is malicious. Remove it and rotate any credentials it could have accessed.
npm uninstall css-dwsawd-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 prevent the execution of this malicious code by avoiding the use of the css-dwsawd-polyfill package altogether. If it is already in use, consider replacing it with a legitimate alternative that does not pose security risks.
Conclusion
The css-dwsawd-polyfill package contains a critical vulnerability due to embedded malicious code that can execute unauthorized commands. It is essential to remove this package from your project and monitor for any updates or patches. Utilizing tools like Vulert can help you stay informed about vulnerabilities in your dependencies.
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FAQ
It is an npm module that mimics a legitimate Wix thunderbolt polyfill but contains malicious code.
The code executes shell commands to gather system information and sends it to an external server.
Using this package can lead to unauthorized data exposure and compromise of the host system.
You can use Vulert's playground at Vulert Scanner to check for vulnerabilities in your application without needing to sign up.
Remove the css-dwsawd-polyfill package from your project immediately and look for a legitimate alternative.
