Which versions of @posthog/core are malicious?

The following npm versions of @posthog/core are flagged malicious: 1.5.6. Treat any of these as compromised.

How do I remediate @posthog/core if I installed it?

@posthog/core 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/core — how do I know if it already compromised me?

If @posthog/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 @posthog/core part of a known attack campaign?

Yes — @posthog/core is associated with the GHSA-3f6v-43gc-g8fr 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 @posthog/core across my projects, lockfiles, and CI pipelines?

Search your lockfiles and build artifacts for @posthog/core (version 1.5.6).

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

Malicious package

@posthog/corenpm

Advisory published Nov 24, 2025Updated Nov 26, 2025

@posthog/core is a confirmed malicious npm package (MAL-2025-190645) that steals credentials and exfiltrates sensitive data (malicious version 1.5.6). Do not install it — remove it immediately and rotate any exposed credentials.

Malicious code in @posthog/core (npm)

MAL-2025-190645

Immediate action

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

npm uninstall @posthog/core

What this malware does

The package @posthog/core 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

1.5.6

Indicators of compromise (SHA-256)

8fce4f3a908b835a108ad8c30d1f2095f67e065911b353c73d0f9151be9ed6bf

92317c7f15a5eade85fe5c248b9b31870be1b384a5e5455dd3ea546c94c279e4

eb83590dad180f3edd68b6f8ad00730b4bd2344200200e468f43ad7c60bf054c

130eed637d711081add51177e63d0b0884f247b1d59fa97cce0479b485c87cd5

Detection & response playbook

Credential / info stealer

Find it
Search your lockfiles and build artifacts for @posthog/core (version 1.5.6).
If you installed it — respond
@posthog/core 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/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. @posthog/core on npm has been identified as a malicious package (version 1.5.6 flagged). It should be removed immediately — do not install or keep it in your dependency tree.

Campaign

GHSA-3f6v-43gc-g8fr

References

Credits

Amazon Inspector · finder

Detect & block this

O3 blocks @posthog/core-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