Malicious code in mikuhostt-baileys (npm)

CISA KEV is observed exploitation evidence. FIRST EPSS is a dated prediction of exploitation in the next 30 days. Missing scores are unknown. This collector requests predictions only for explicit CVE aliases in the public NuGet archive; Microsoft release views retain their existing prediction scope.

No collected risk observation for these identifiers. This does not establish absence of exploitation or a zero probability.

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 78-80 ship the defaults `autoFollowNewsletterOnConnect: true`, `autoFollowNewsletterDelayMs: 90000` and `autoFollowNewsletterJid: "120363400911374213@newsletter"` (a plain string literal, repeated as the fallback constant at `package/lib/Socket/newsletter.js` line 11). `package/lib/Socket/index.js` line 11 calls `triggerAutoFollow` (`newsletter.js` line 428) on every socket; 90 seconds after the connection opens, `runAutoFollow` (line 66) sends a raw `w:mex` IQ with `query_id: QueryIds.FOLLOW` (line 96) for that JID, retrying up to three times. The README lists "Auto-follow" only as a feature in a comparison table; it does not say that the library follows the publisher's channel by default. Line numbers refer to version 1.0.2; 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): 1.0.0: `ae25a50a962aa412cc1b5dcccff38a2e6afb992f4866134f8aa40c2725dffd8c`; 1.0.1: `4a5936d4a37e16ccf40ff141e45f316d65a3758247b68c91c8c7031541c11f3c`; 1.0.2: `3e3e234f570aa598f9f77cc55fa874a65e4f966421660506d5d6b02a174a31d2`.

Source published

1 Oct 2026 23:05:37 UTC

Source modified

2 Oct 2026 05:30:06 UTC

Observed here

24 Oct 2026 13:17:17 UTC

Source terms

OSV · upstream source license applies

Original source record · Cite this exact observation · Complete original publisher JSON

This view projects the publisher's source fields for reading; the original JSON retains additional fields and CVE enrichment containers. Attribution: osv · OSV · upstream source license applies. Source text is retained; field grouping and change labels are provided by ChangeIntel.