Which versions of flatten-unflatten are malicious?

The following npm versions of flatten-unflatten are flagged malicious: 1.0.1, 1.0.2. Treat any of these as compromised.

How do I remediate flatten-unflatten if I installed it?

flatten-unflatten 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.

I already installed flatten-unflatten — how do I know if it already compromised me?

If flatten-unflatten was ever installed, its post-install/runtime payload may have already executed. O3's L7 egress monitoring and runtime eBPF sensors detect the credential exfiltration or command-and-control callback after install and block the malicious outbound channel, so you catch and contain the actual compromise — not just the presence of the package.

Is flatten-unflatten part of a known attack campaign?

Yes — flatten-unflatten is associated with the GHSA-3rw9-37g7-xvr5 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 flatten-unflatten across my projects, lockfiles, and CI pipelines?

Scan your lockfiles (package-lock.json, pnpm-lock.yaml, yarn.lock, requirements.txt, poetry.lock, etc.) and build artifacts for flatten-unflatten (2 malicious versions). O3 Security's supply-chain scanner checks every dependency against known-malicious package intelligence at install time and in CI, flagging flatten-unflatten across your stack and pipelines.

Malicious package

flatten-unflattennpm

Malicious code in flatten-unflatten (npm) Remove it immediately and rotate any exposed credentials.

MAL-2025-191095

Immediate action

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

npm uninstall flatten-unflatten

What this malware does

The package flatten-unflatten was found to contain malicious code.

Any computer that has this package installed or running should be considered fully compromised. All secrets and keys stored on that computer should be rotated immediately from a different computer. The package should be removed, but as full control of the computer may have been given to an outside entity, there is no guarantee that removing the package will remove all malicious software resulting from installing it.

This package was compromised by the Sha1-Hulud: The Second Coming NPM worm. The malicious payload steals tokens and credentials and publishes them to GitHub. The worm will propogate itself to NPM packages the user owns and establish persistence is a GitHub action. The package may also destroy the user's home directory.

Malicious versions

2 flagged

1.0.11.0.2

Indicators of compromise (SHA-256)

981bcfc50bb3770af24183ffdbf560d45b6a0f84300049ebe36ac05ba7509703

371149b9c29f4411da812dc9c6f10d226db75c9c8f2994e0cfdacfc15fd65a61

96678bbed20be5d500dc65bda769b41f7d3666a18c8a76262aca5ed79ef584fd

Detection & response playbook

Credential / info stealer

Find it
Scan your lockfiles (package-lock.json, pnpm-lock.yaml, yarn.lock, requirements.txt, poetry.lock, etc.) and build artifacts for flatten-unflatten (2 malicious versions). O3 Security's supply-chain scanner checks every dependency against known-malicious package intelligence at install time and in CI, flagging flatten-unflatten across your stack and pipelines.
If you installed it — respond
flatten-unflatten 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 flatten-unflatten was ever installed, its post-install/runtime payload may have already executed. O3's L7 egress monitoring and runtime eBPF sensors detect the credential exfiltration or command-and-control callback after install and block the malicious outbound channel, so you catch and contain the actual compromise — not just the presence of the package.
How O3 protects you
O3 blocks flatten-unflatten before install through its supply-chain scanner, and if it has already run, detects and severs the exfiltration or C2 callback at runtime through L7 egress monitoring and eBPF.

Frequently asked questions

No. flatten-unflatten on npm has been identified as a malicious package (versions 1.0.1, 1.0.2 flagged). It should be removed immediately — do not install or keep it in your dependency tree.

Campaign

GHSA-3rw9-37g7-xvr5

References

Credits

Amazon Inspector · finder

Detect & block this

O3 blocks flatten-unflatten-class packages before install and in CI — and if it already ran, its runtime egress monitoring catches the credential exfiltration and severs the channel.

Malware detection Runtime egress monitoring