Critical Malicious Code Vulnerability in @bingads-webui-theme-2018/theme-fluent Package

Summary

19/01/2026
CRITICAL
No i
Critical
Not published

MAL-2026-347: Malicious code in @bingads-webui-theme-2018/theme-fluent (npm). Affected versions are not published. No fix is published. How to fix ↓

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Background

The @bingads-webui-theme-2018/theme-fluent package is part of the npm ecosystem, designed to provide a theme for Bing Ads web UI applications. It is utilized by developers to enhance the user interface of their applications. However, this package has been identified as containing malicious code, posing a significant security risk to any system that has it installed.

Vulnerability Detail

The vulnerability originates from the presence of embedded malicious code within the @bingads-webui-theme-2018/theme-fluent package. This code can compromise the entire system, allowing unauthorized access to sensitive information such as secrets and keys. The malicious nature of this code means that any computer running this package should be considered fully compromised, and there is no guarantee that simply removing the package will eliminate all traces of the malicious software.

How To Fix

This package is malicious. Remove it and rotate any credentials it could have accessed.

npm uninstall @bingads-webui-theme-2018/theme-fluent

If 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

Currently, there are no effective workarounds to mitigate the risks posed by this vulnerability other than removing the package and rotating any compromised credentials.

Conclusion

The @bingads-webui-theme-2018/theme-fluent package has been identified as containing malicious code, posing a severe security threat. Immediate action is required to uninstall the package and secure any sensitive information. Regular monitoring for updates and vulnerabilities is crucial to maintaining system security.

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FAQ

Immediately uninstall the package using npm uninstall @bingads-webui-theme-2018/theme-fluent and rotate any sensitive information stored on the affected system.

You can use Vulert, which monitors and alerts for open-source vulnerabilities in your software. Check your application against this vulnerability using the Vulert playground at Vulert Scanner.

Failure to address this vulnerability can lead to unauthorized access to sensitive data, complete system compromise, and potential data breaches.

As of now, there is no patched version available. The best course of action is to uninstall the package and monitor for updates.

While removing the package is essential, it does not guarantee that all malicious software has been eliminated. A thorough security audit of your system is recommended.

How To Fix

This package is malicious. Remove it and rotate any credentials it could have accessed.

npm uninstall @bingads-webui-theme-2018/theme-fluent

If 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 →

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