Which versions of pewter-constants are malicious?

The following npm versions of pewter-constants are flagged malicious: 9999.0.0. Treat any of these as compromised.

How do I remediate pewter-constants if I installed it?

Remove pewter-constants 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 pewter-constants — how do I know if it already compromised me?

If pewter-constants 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 pewter-constants part of a known attack campaign?

Yes — pewter-constants is associated with the IN-MAL-2026-004369 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 pewter-constants across my projects, lockfiles, and CI pipelines?

Search your lockfiles and build artifacts for pewter-constants (version 9999.0.0).

Malicious package

pewter-constantsnpm

Advisory published May 23, 2026Updated May 26, 2026

pewter-constants is a confirmed malicious npm package (MAL-2026-4637) that executes malicious code on install (malicious version 9999.0.0). Do not install it — remove it immediately and rotate any exposed credentials.

Malicious code in pewter-constants (npm)

MAL-2026-4637

Immediate action

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

npm uninstall pewter-constants

What this malware does

On npm install, a preinstall hook in callback.js collects os.hostname(), os.userInfo().username, process.cwd(), the configured npm registry (npm_config_registry), and CI repo identifiers (GITHUB_REPOSITORY, CI_PROJECT_PATH, BUILD_REPOSITORY_NAME) and HTTP-GETs them to http://75.119.137.232:31337/depconfuse. The package is shaped as a dependency-confusion squat: version 9999.0.0 to win semver resolution against an internal package of the same name, an empty index.js (module.exports = {}), and placeholder author/description metadata (Security Researcher, Security research placeholder). Any build that resolves pewter-constants from the public registry will install this package and silently leak its internal registry URL, CI repo path, and host/user identity to a third-party operator over plain HTTP. The 'security research' framing in the metadata does not change the installer-side impact — internal infrastructure is fingerprinted and disclosed without consent.

Malicious versions

1 flagged

9999.0.0

Indicators of compromise (SHA-256)

3c9f898fe8ed95b1d549bfff91d7c0dda0f75ada1c32a58af144940cf28b23c5

Detection & response playbook

Malicious package

Find it
Search your lockfiles and build artifacts for pewter-constants (version 9999.0.0).
If you installed it — respond
Remove pewter-constants 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 pewter-constants 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. pewter-constants on npm has been identified as a malicious package (version 9999.0.0 flagged). It should be removed immediately — do not install or keep it in your dependency tree.

Campaign

IN-MAL-2026-004369

References

npmjs.com

Credits

Amazon Inspector · finder

Detect & block this

O3 blocks pewter-constants-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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