Which versions of @posthog/lemon-ui are malicious?

The following npm versions of @posthog/lemon-ui are flagged malicious: 0.0.1. Treat any of these as compromised.

How do I remediate @posthog/lemon-ui if I installed it?

@posthog/lemon-ui 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 @posthog/lemon-ui — how do I know if it already compromised me?

If @posthog/lemon-ui 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.

How do I find @posthog/lemon-ui across my projects, lockfiles, and CI pipelines?

Search your lockfiles and build artifacts for @posthog/lemon-ui (version 0.0.1).

Part of a larger attack: @posthog published 56 malicious packages. See the full campaign →

Malicious package

@posthog/lemon-uinpm

Advisory published Nov 25, 2025Updated Dec 1, 2025

@posthog/lemon-ui is a confirmed malicious npm package (MAL-2025-191295) that steals credentials and exfiltrates sensitive data (malicious version 0.0.1). Do not install it — remove it immediately and rotate any exposed credentials.

Malicious code in @posthog/lemon-ui (npm)

MAL-2025-191295

Immediate action

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

npm uninstall @posthog/lemon-ui

What this malware does

The package @posthog/lemon-ui was found to contain malicious code.

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

0.0.1

Indicators of compromise (SHA-256)

6b1d5aea355f6b18ee4fc22bd93bdc289a2011dac9c66f8ec0d3500342578e26

bba1e7fb74f376bd3b56d7c910331af7b46fa8c392e697e08f858b837112e061

Detection & response playbook

Credential / info stealer

Find it
Search your lockfiles and build artifacts for @posthog/lemon-ui (version 0.0.1).
If you installed it — respond
@posthog/lemon-ui 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 @posthog/lemon-ui 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. @posthog/lemon-ui on npm has been identified as a malicious package (version 0.0.1 flagged). It should be removed immediately — do not install or keep it in your dependency tree.

References

Credits

Amazon Inspector · finder

Detect & block this

O3 blocks @posthog/lemon-ui-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