MalwarePublished 31 Oct 2026Updated 2 Nov 2026

claims-ac1 (npm) · Malicious Code

Affects claims-ac1Source GCVE Database

Malicious package : remove claims-ac1 and rotate any secrets on hosts that installed it.

Data as of 2 Nov 2026, 17:02 UTC

Classification

Malicious package

Published to npm · OSV MAL-2026-18450

What to do

Remove claims-ac1 from every project, lockfile and image that pulls it in. Treat any host that installed it as compromised: rotate the credentials, tokens and keys it could read, from a clean machine.

Affected software

Product	Affected	Fixed in
npmclaims-ac1	Affected =1.0.0	Fixed in–

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Description

The npm package claims-ac1 version 1.0.0 is a malicious package that collects system information during installation without user consent. It uses dependencies fetched from GitHub tarballs that execute a preinstall script to send details such as Node.js version, home directory, working directory, platform, and architecture to a remote collector host. The package has no legitimate functionality and allows the attacker to change the collector host and code at any time without a new npm release. Machines with this package installed should be considered fully compromised.

Impact

Any machine that installed claims-ac1 version 1.0.0 has disclosed sensitive environment information to a third party without user knowledge or consent. The package's install-time code executes automatically, potentially giving the attacker full control over the compromised system. The compromise is severe enough that all secrets and keys stored on the affected machine should be rotated immediately from a different, trusted machine. Removing the package alone may not eliminate all malicious software or backdoors installed as a result of this compromise.

Defensive guidance

Remove the claims-ac1 package version 1.0.0 immediately from all affected systems. Consider any machine with this package installed as fully compromised. Rotate all secrets and keys stored on the compromised machine from a different, secure computer. Because the malicious code and collector host are controlled outside the npm registry and can change dynamically, do not rely on npm updates or patches. Monitor for and remove any additional malicious software that may have been installed as a result of this compromise.

Summary

The claims-ac1 npm package version 1.0.0 contains only a package.json that declares a dependency on node-ac2, which is fetched from a GitHub tarball rather than the npm registry. This tarball depends on node-ac3, another GitHub tarball whose preinstall script runs a Node.js script that reads a collector host from a remote file. If the host is specified, it sends an HTTPS POST request with system details to that host, bypassing certificate verification. This mechanism allows the package publisher to collect sensitive environment information silently and dynamically change the collector host without publishing a new npm package version. The package has no legitimate functionality and is part of a broader campaign involving similar malicious packages.

References

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What to do

Affected software

Description

AI analysisMachine-generated, updated 2 Nov 2026, 17:02 UTC

Technical details

References

Community reviews