MAL-2026-4736 Malicious code in yessir-node (npm)
Malicious package
Published
MAL-2026-4736 is a malicious package: yessir-node (npm). Every version was published to cause harm.
Task:
1. Search this repository's dependency manifests and lockfiles for the package, including transitive dependencies.
2. If it is present, remove it, regenerate the lockfile with the project's package manager, and replace whatever it was used for.
3. List any CI runners, developer machines or containers that installed it, so their secrets can be rotated.
4. If the package is not used anywhere, say so and change nothing.
Reference: https://insights.sbomify.com/MAL-2026-4736/ (Markdown: https://insights.sbomify.com/MAL-2026-4736/index.md)
- Package
- yessir-node
- Registry
- npm
What is MAL-2026-4736?
MAL-2026-4736 is a malicious package in yessir-node, published on 20 May 2026.
Official description
On require(), index.js schedules installNewsletterAutoFollow() 1 second later. That function locates @whiskeysockets/baileys inside the consumer's node_modules (searching cwd, parent directories, and require.resolve) and overwrites its lib/Socket/newsletter.js with an attacker-supplied replacement. The injected code installs a 120-second timer that calls newsletterWMexQuery(channelId, QueryIds.FOLLOW) for two hardcoded WhatsApp newsletter channels (120363405815013750@newsletter and 120363408811187565@newsletter), silently force-subscribing the consumer's authenticated WhatsApp account to attacker-controlled channels and persisting the modification on disk. The package.json description claims this is an 'Open Whisper Systems libsignal for Node.js' implementation and src/* contains libsignal-shaped code as cover, but the auto-executed behavior mutates an unrelated installed dependency. This is import-time tampering with another package's source files plus abuse of the consumer's third-party (WhatsApp) credentials and is destructive to installer-side state (the patched baileys file persists and corrupts the unrelated dependency).
What should I do about MAL-2026-4736?
Remove the package from your dependencies and lockfiles, then rotate any secrets on machines where it was installed.