Covert Channel Subscription Vulnerability in xzbails Package
Summary
MAL-2026-17410: Malicious code in xzbails (npm). Affects xzbails versions 0.0.3 – 0.0.5. No fix is published. How to fix ↓
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Background
The xzbails package is a part of a larger family of forks derived from the Baileys WhatsApp Web library. It is designed to facilitate interactions with WhatsApp's socket layer. However, this package has been identified as malicious, injecting covert actions that exploit the user's authenticated WhatsApp session to subscribe them to unwanted channels without their consent.
Vulnerability Detail
The vulnerability stems from the xzbails package injecting malicious code into the WhatsApp socket layer. Upon connection, this code executes an authenticated 'w:mex' FOLLOW query targeting attacker-controlled WhatsApp Channel/Newsletter JIDs. The targeted JIDs are obfuscated using various techniques, making them difficult to detect in source reviews. This malicious action allows attackers to gain subscribers for their channels using the victim's WhatsApp account, without exfiltrating credentials or executing arbitrary remote code.
How To Fix
This package is malicious. Remove it and rotate any credentials it could have accessed.
npm uninstall xzbailsIf 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 xzbails package from your project entirely until a secure version is confirmed. Use the following command to uninstall the package: npm uninstall xzbails.
Conclusion
The xzbails package poses a significant risk due to its ability to exploit users' WhatsApp sessions for unauthorized channel subscriptions. It is essential to take immediate action by updating or removing the package to safeguard your account and privacy.
See every vulnerability recorded for xzbails →
FAQ
xzbails is a fork of the Baileys WhatsApp Web library, designed for interacting with WhatsApp's socket layer.
The vulnerability allows attackers to subscribe your account to their channels without your consent, using your authenticated session.
You should immediately update the package to the latest version or uninstall it to mitigate the risk.
Yes, you can use Vulert's playground at Vulert Scanner to check for vulnerabilities in your application without needing to sign up.
The malicious code uses various obfuscation techniques such as plain string literals, base64 encoding, and runtime char-code arrays to hide the target JIDs.
