buffer-util-internalnpm
Advisory published Updated
buffer-util-internal is a confirmed malicious npm package (MAL-2026-10151) that steals credentials and exfiltrates sensitive data (malicious versions 1.0.13, 1.0.14). Do not install it — remove it immediately and rotate any exposed credentials.
Malicious code in buffer-util-internal (npm)
What this malware does
Package impersonates Feross Aboukhadijeh's widely-used buffer package, copying its author, repository, contributors, and description metadata while publishing under the name buffer-util-internal. The main module index.js contains a top-level IIFE that base64-decodes a hardcoded URL (decoding to https://www.jsonkeeper.com/b/PT0ON), fetches a JSON document from that anonymous paste host, and passes the response's content field directly to eval. The destination URL is hidden behind a variable named tokenStringRe with a misleading // Random string to generate strong random value comment, alongside a second base64 string referencing a sibling paste id. Because the fetched content is attacker-mutable, every consumer that requires this package executes whatever JavaScript the paste host serves at that moment — a full remote code execution primitive on the installer at require time. The package also declares unusual dependencies (axios, execp, request) inconsistent with the legitimate buffer package.
Malicious versions
Indicators of compromise (SHA-256)
Detection & response playbook
Credential / info stealerFind it
Search your lockfiles and build artifacts for buffer-util-internal (2 malicious versions).
If you installed it — respond
buffer-util-internal is built to steal secrets, so assume every credential the build or runtime could read is compromised. Remove it from your project and lockfile, then rotate ALL exposed secrets — npm/registry tokens, cloud keys, CI/CD secrets, SSH keys, and any .env values — from a known-clean machine. Audit logs for unauthorized use of those credentials.
Did it already run?
If buffer-util-internal 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
Campaign
References
Credits
- Amazon Inspector · finder
Detect & block this
O3 blocks buffer-util-internal-class packages before install and in CI — and if it already ran, its runtime egress monitoring catches the credential exfiltration and severs the channel.