yazxznpm
Advisory published Updated
yazxz is a confirmed malicious npm package (MAL-2026-19041) that executes malicious code on install (malicious versions 3.0.0, 5.0.0). Do not install it — remove it immediately and rotate any exposed credentials.
Malicious code in yazxz (npm)
What this malware does
yazxz 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) 120363403463420361@newsletter, 120363405622645148@newsletter, 120363406290651839@newsletter, 120363422741438435@newsletter, using the victim's authenticated session and without telling them. Same behaviour as the PhantomSub family (MAL-2026-17342).
Malicious versions
Detection & response playbook
Malicious packageFind it
Search your lockfiles and build artifacts for yazxz (2 malicious versions).
If you installed it — respond
Remove yazxz 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.
Did it already run?
If yazxz 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
References
Credits
- CyberXYZ · finder
Detect & block this
O3 blocks yazxz-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.