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Malicious package

yuuki-baileysnpm

Advisory published Updated

yuuki-baileys is a confirmed malicious npm package (MAL-2026-19044) that executes malicious code on install (malicious versions 1.0.1, 2.0.0, 2.1.0). Do not install it — remove it immediately and rotate any exposed credentials.

Malicious code in yuuki-baileys (npm)

MAL-2026-19044
Immediate action
Remove the package, then rotate any secrets the build/runtime could reach.
npm uninstall yuuki-baileys

What this malware does

yuuki-baileys 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 Yuuki-baileys/lib/Socket/newsletter.js, lib/Socket/newsletter.js sends the WhatsApp w:mex FOLLOW query for the channel ID(s) 120363406005175144@newsletter, using the victim's authenticated session and without telling them. Same behaviour as the PhantomSub family (MAL-2026-17342).

Malicious versions

3 flagged
1.0.12.0.02.1.0

Detection & response playbook

Malicious package
  1. Find it

    Search your lockfiles and build artifacts for yuuki-baileys (3 malicious versions).

  2. If you installed it — respond

    Remove yuuki-baileys 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 yuuki-baileys 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. yuuki-baileys on npm has been identified as a malicious package (versions 1.0.1, 2.0.0, 2.1.0 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 yuuki-baileys-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

yuuki-baileys (npm) malicious package — MAL-2026-19044 | O3 Security