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Malicious package

baileys-web4.0npm

Advisory published Updated

baileys-web4.0 is a confirmed malicious npm package (MAL-2026-18946) that executes malicious code on install (malicious version 0.1.0). Do not install it — remove it immediately and rotate any exposed credentials.

Malicious code in baileys-web4.0 (npm)

MAL-2026-18946
Immediate action
Remove the package, then rotate any secrets the build/runtime could reach.
npm uninstall baileys-web4.0

What this malware does

baileys-web4.0 is a fork of the Baileys WhatsApp Web library that silently subscribes the installer's own WhatsApp account to WhatsApp Channels chosen by the publisher. When the socket connects, code in lib/Socket/newsletter.js sends the WhatsApp w:mex FOLLOW query for the channel ID(s) 120363405637529316@newsletter, using the victim's authenticated session and without telling them. Same behaviour as the PhantomSub family (MAL-2026-17342).

Malicious versions

1 flagged
0.1.0

Detection & response playbook

Malicious package
  1. Find it

    Search your lockfiles and build artifacts for baileys-web4.0 (version 0.1.0).

  2. If you installed it — respond

    Remove baileys-web4.0 from your project and lockfile, then assume any secrets accessible to the build or runtime were exposed: rotate API keys, tokens, and credentials, and audit for unexpected outbound activity or persistence.

  3. Did it already run?

    If baileys-web4.0 was installed, its post-install payload may already have run. Removing the package does not undo that — check outbound connections and credential use from the install window onward.

Frequently asked questions

No. baileys-web4.0 on npm has been identified as a malicious package (version 0.1.0 flagged). It should be removed immediately — do not install or keep it in your dependency tree.

References

Credits

  • CyberXYZ · finder

Detect & block this

O3 blocks baileys-web4.0-class packages before install and in CI — and if it already ran, its runtime egress monitoring catches the malicious outbound activity and severs the channel.

Explore

baileys-web4.0 (npm) malicious package — MAL-2026-18946 | O3 Security