Vulnerability MAL-2026-17441

This package is a fork of the Baileys WhatsApp Web library (npm) and belongs to the "PhantomSub" family described by OX Security in September 2026: the publisher injected code that, without the installer asking, uses the installer's own authenticated WhatsApp session to subscribe that account to WhatsApp Channels (newsletters) the publisher chose, by sending the WhatsApp w:mex FOLLOW query (query_id 7871414976211147) for each target channel JID.

package/lib/Defaults/index.js lines 79-81 ship the defaults autoFollowNewsletterOnConnect: true, autoFollowNewsletterDelayMs: 90000 and autoFollowNewsletterJid: "120363400911374213@newsletter" (a plain string literal). package/lib/Socket/index.js line 11 calls triggerAutoFollow (package/lib/Socket/newsletter.js line 428) on every socket, which waits 90 seconds after the connection opens and runs runAutoFollow (line 66), sending a raw w:mex IQ with query_id: QueryIds.FOLLOW (line 96) for that JID, retrying up to three times. The follow is on by default and the README does not mention it; a user would have to find and set the undocumented autoFollowNewsletterOnConnect: false to avoid it. In 0.3.0 the fallback constant at newsletter.js line 11 is 120363418617842480@newsletter, but the shipped default config value 120363400911374213@newsletter takes precedence in both versions.

Line numbers refer to version 0.3.1; the same code is present in every published version listed under affected.

Static review of the published tarball(s) found no code that sends WhatsApp credentials or session keys off-host, no install-time payload (the only install hook is Baileys' stock Node.js version check in engine-requirements.js), and no persistence; the payload runs when an application creates a WhatsApp socket with the library. The harm is the covert use of the victim's account to inflate the publisher's channel subscribers.

SHA-256 of the published npm tarball(s): 0.3.0: e274c9056c7891ebcfc175798a97a1302b93294ba3877f7c03ef6bc19753e0e1; 0.3.1: 3ae57ea60d9da75b5653743ea4fdc5f74e2de718078a5ac735f3d8b22b260136.