Malicious Code Injection in css-display-reading-polyfill: A Security Threat
Summary
MAL-2026-17549: Malicious code in css-display-reading-polyfill (npm). Affects css-display-reading-polyfill versions 1.0.0. No fix is published. How to fix ↓
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Background
The css-display-reading-polyfill is an npm package designed to enhance the display of reading content in web applications. It is commonly used in various projects to ensure a consistent user experience across different platforms. However, this package has been found to contain malicious code that compromises the security of applications utilizing it.
Vulnerability Detail
The vulnerability originates from a malicious payload embedded in the package's payload.bundle.min.js file. Upon loading, this file executes an Immediately Invoked Function Expression (IIFE) that runs shell commands to gather sensitive information about the host system, including user identity and operating system details. This information is then sent to an attacker-controlled endpoint, posing significant risks such as data exfiltration and unauthorized access to system information. The package impersonates an internal module used by Wix, making it a dependency-confusion attack that exploits the trust placed in internal package names.
How To Fix
This package is malicious. Remove it and rotate any credentials it could have accessed.
npm uninstall css-display-reading-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 the malicious code by removing the css-display-reading-polyfill package from your project. Use the following command to uninstall it: npm uninstall css-display-reading-polyfill. Additionally, monitor your application for any suspicious activity until a fix is implemented.
Conclusion
The css-display-reading-polyfill package contains a serious vulnerability due to embedded malicious code that can compromise the security of applications. It is essential to take immediate action by updating or removing the package to protect your system from potential threats.
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FAQ
It is an npm package used to improve the display of reading content in web applications.
The malicious code collects sensitive information from the host system and sends it to an attacker-controlled endpoint.
The risks include data exfiltration, unauthorized access to system information, and potential exploitation of the affected application.
You can use Vulert, which monitors and alerts for open-source vulnerabilities in real-time. Visit Vulert Scanner to check your application without needing to sign up.
If no patched version is available, consider removing the package and replacing it with a secure alternative to mitigate risks.
