npm · Malicious package advisory
Malwarefastify-addone
MAL-2026-10098
Malicious code in fastify-addone (npm)
Details
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_-= Per source details. Do not edit below this line.=-_
## Source: amazon-inspector (21b9e477cff478ab071039c18c3adb6577a07cc1d82687b9e7d7cd2594dc9ddf)
The package presents itself as fastify-plugin (name fastify-addone, repository/homepage/bugs fields point at fastify/fastify-plugin) and copies that project's source with a malicious statement inserted. lib/getPluginName.js contains a top-level statement that base64-decodes a URL via atob, fetches the JSON at https://www.jsonkeeper.com/b/HDXPP, and passes the returned content field to eval. This executes attacker-controlled JavaScript in the caller's process on any require('fastify-addone') (directly or via plugin.js). The destination is an anonymous, mutable third-party JSON-hosting service — not the publisher's infrastructure — and the payload URL is hidden behind base64 to evade casual review.
Compromised versions (2)
- 5.1.0
- 5.1.1
Any computer that installed or ran a compromised version should be considered fully compromised. Rotate every secret on that machine from a clean environment.