Malicious Code Execution in css-txedrf-polyfill Package
Summary
MAL-2026-17558: Malicious code in css-txedrf-polyfill (npm). Affects css-txedrf-polyfill versions 1.0.0. No fix is published. How to fix ↓
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Background
The css-txedrf-polyfill package is an npm library designed to provide polyfills for CSS features. It is commonly used in web development to ensure compatibility across different browsers. However, this package has been found to contain malicious code that executes OS reconnaissance commands, posing a significant security risk to users who integrate it into their applications.
Vulnerability Detail
The vulnerability originates from the thunderboltRegistry.js file within the css-txedrf-polyfill package. Upon requiring this module, it executes an Immediately Invoked Function Expression (IIFE) that runs various OS commands (such as id, whoami, uname -a, ifconfig/ip addr, and cat /etc/hosts) using child_process.execSync. The output is URL-encoded and sent to a hardcoded attacker-controlled endpoint via HTTP. This malicious behavior can lead to unauthorized data exfiltration and compromise the security of the host system.
How To Fix
This package is malicious. Remove it and rotate any credentials it could have accessed.
npm uninstall css-txedrf-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 avoid using the css-txedrf-polyfill package altogether or replace it with a trusted alternative that does not contain malicious code. Additionally, you can monitor your application for vulnerabilities using tools like Vulert, which analyzes your package-lock.json file for potential threats.
Conclusion
The css-txedrf-polyfill package contains a serious vulnerability that allows for the execution of malicious code, posing a risk to users' systems. It is crucial to update the package to a patched version or implement workarounds to protect your application from potential threats.
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FAQ
css-txedrf-polyfill is an npm package that provides polyfills for CSS features to ensure compatibility across different browsers.
The vulnerability allows malicious code to execute OS commands on your system, potentially leading to data theft and system compromise.
You can use the Vulert playground to analyze your package-lock.json file for vulnerabilities without needing to sign up.
If an immediate update is not possible, consider removing the package or replacing it with a secure alternative until a patch is available.
Detailed information about this vulnerability can be found in the Open Source Vulnerability database and related security advisories.
