MalwarePublished 9 Jul 2026

mchain-sdk (npm) · Malicious Code

Affects mchain-sdkSource GCVE Database

Malicious package : remove mchain-sdk and rotate any secrets on hosts that installed it.

Data as of 10 Jul 2026, 10:10 UTC

Classification

Malicious package

Published to npm · OSV MAL-2026-10012

What to do

Remove mchain-sdk 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
npmmchain-sdk	Affected =4.2.5	Fixed in–

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Description

The mchain-sdk npm package version 4.2.5 is a malicious typosquatting package that executes attacker-controlled JavaScript code both during installation and at runtime. It fetches and runs remote code from a mutable anonymous paste URL disguised as an API key, leading to full system compromise. The package mimics a legitimate library to evade detection. Removal alone may not fully remediate the compromise, and all secrets on affected systems should be rotated immediately.

Impact

Systems with mchain-sdk version 4.2.5 installed or running are fully compromised, as the package executes remote attacker-controlled code with the privileges of the user running the package. This can lead to unauthorized access, data exfiltration, and control over the affected system. Secrets and keys stored on the compromised system are at risk and must be considered exposed.

Defensive guidance

Immediate removal of the mchain-sdk package version 4.2.5 is required. However, removal alone may not eliminate all malicious artifacts or backdoors installed by the package. It is critical to rotate all secrets, keys, and credentials that were stored or used on the compromised system, using a separate, trusted device. Monitor for any suspicious activity and consider a full system rebuild if compromise is suspected.

Summary

The mchain-sdk package (version 4.2.5) is a malicious npm package that contains a postinstall hook executing a top-level async immediately-invoked function expression (IIFE) which base64-decodes a URL stored in its configuration. This URL points to an anonymous paste on jsonkeeper.com, from which it fetches attacker-controlled JavaScript code and executes it in a detached child node process. Additionally, the package's main module imports this malicious code immediately on load, triggering the payload even if npm install is run with --ignore-scripts. The package is a typosquatting repackage of the legitimate uhop/stream-chain library, designed to evade casual review by cloning its API surface and documentation. This results in full compromise of any system that installs or runs this package.

References

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What to do

Affected software

Description

AI analysisMachine-generated, updated 10 Jul 2026, 10:10 UTC

Technical details

References

Community reviews