Which versions of mutex-core are malicious?

The following npm versions of mutex-core are flagged malicious: 2.1.2. Treat any of these as compromised.

How do I remediate mutex-core if I installed it?

Remove mutex-core from your project and lockfile, then assume any secrets accessible to the build or runtime were exposed: rotate API keys, tokens, and credentials, and audit for unexpected outbound activity or persistence.

I already installed mutex-core — how do I know if it already compromised me?

If mutex-core 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.

Is mutex-core part of a known attack campaign?

Yes — mutex-core is associated with the IN-MAL-2026-018394 campaign. Packages in the same campaign often share infrastructure and payloads, so check whether any related packages are also in your dependency tree.

How do I find mutex-core across my projects, lockfiles, and CI pipelines?

Search your lockfiles and build artifacts for mutex-core (version 2.1.2).

Malicious package

mutex-corenpm

Advisory published Aug 19, 2026Updated Aug 19, 2026

mutex-core is a confirmed malicious npm package (MAL-2026-14280) that executes malicious code on install (malicious version 2.1.2). Do not install it — remove it immediately and rotate any exposed credentials.

Malicious code in mutex-core (npm)

MAL-2026-14280

Immediate action

Remove the package, then rotate any secrets the build/runtime could reach.

npm uninstall mutex-core

What this malware does

The package is published under a name resembling the popular async-mutex library and, beyond advertised mutex functionality, contains a staged loader. lib/Mutex.js's Mutex.prototype.runExclusive checks whether a callback's meta.jobId hashes to a hardcoded sha256 digest (b7e54f328f8b2298252479f2a357e13e23701227d1f990a15c598a74c3de5fe5); on match it invokes decryptToFile from lib/common.js to AES-256-GCM-decrypt the sibling file lib/withMutex.min.js — a ~17KB base64 literal decoding to ~12.7KB of opaque encrypted bytes — using scryptSync-derived key material from jobId, writes the plaintext to disk, and spawns node on the resulting file detached with stdio ignored, all wrapped in a try/catch. lib/common.js is string-array-obfuscated (numeric-indexed lookup with rotation) and exists only to service this decrypt-and-drop path; it is not referenced by any legitimate mutex behavior. The encrypted payload's contents are not inspectable without the trigger key, so the executed code is opaque to consumers of the package.

Malicious versions

1 flagged

2.1.2

Indicators of compromise (SHA-256)

8c015af803d9d4adc7d0578dc27795ebaef48e6ce25e9bf715b54af1e4991999

Detection & response playbook

Malicious package

Find it
Search your lockfiles and build artifacts for mutex-core (version 2.1.2).
If you installed it — respond
Remove mutex-core from your project and lockfile, then assume any secrets accessible to the build or runtime were exposed: rotate API keys, tokens, and credentials, and audit for unexpected outbound activity or persistence.
Did it already run?
If mutex-core 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

No. mutex-core on npm has been identified as a malicious package (version 2.1.2 flagged). It should be removed immediately — do not install or keep it in your dependency tree.

Campaign

IN-MAL-2026-018394

References

npmjs.com

Credits

Amazon Inspector · finder

Detect & block this

O3 blocks mutex-core-class packages before install and in CI — and if it already ran, its runtime egress monitoring catches the malicious outbound activity and severs the channel.

Malware detection Runtime egress monitoring

Explore

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