Which versions of css-dedoupe are malicious?

The following npm versions of css-dedoupe are flagged malicious: 0.1.2. Treat any of these as compromised.

How do I remediate css-dedoupe if I installed it?

css-dedoupe 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 css-dedoupe — how do I know if it already compromised me?

If css-dedoupe 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 css-dedoupe part of a known attack campaign?

Yes — css-dedoupe is associated with the GHSA-h8jx-j7rf-fjhh 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 css-dedoupe across my projects, lockfiles, and CI pipelines?

Search your lockfiles and build artifacts for css-dedoupe (version 0.1.2).

Malicious package

css-dedoupenpm

Advisory published Nov 24, 2025Updated Nov 26, 2025

css-dedoupe is a confirmed malicious npm package (MAL-2025-190953) that steals credentials and exfiltrates sensitive data (malicious version 0.1.2). Do not install it — remove it immediately and rotate any exposed credentials.

Malicious code in css-dedoupe (npm)

MAL-2025-190953

Immediate action

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

npm uninstall css-dedoupe

What this malware does

The package css-dedoupe 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

1 flagged

0.1.2

Indicators of compromise (SHA-256)

9bad835f3386b87b3ce781849db6a96394982d6a092ee635c731d854493dd197

7708f95527bfb987e5bf71ee911acffc550f40aff1b046d3249c9504c14fd52f

278d88928134d0116b141de60d0576301fdc35c0aa42e0a560b822c1e02985d3

Detection & response playbook

Credential / info stealer

Find it
Search your lockfiles and build artifacts for css-dedoupe (version 0.1.2).
If you installed it — respond
css-dedoupe 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 css-dedoupe 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. css-dedoupe on npm has been identified as a malicious package (version 0.1.2 flagged). It should be removed immediately — do not install or keep it in your dependency tree.

Campaign

GHSA-h8jx-j7rf-fjhh

References

Credits

Amazon Inspector · finder

Detect & block this

O3 blocks css-dedoupe-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

Explore

All malware advisories How O3 detects malware Vulnerability database