claude-code-base-actionnpm
Advisory published Updated
claude-code-base-action is a confirmed malicious npm package (MAL-2026-3811) that executes malicious code on install (malicious versions 2.0.0, 2.2.2). Do not install it — remove it immediately and rotate any exposed credentials.
Malicious code in claude-code-base-action (npm)
What this malware does
The package claude-code-base-action was found to contain malicious code.
The OpenSSF Package Analysis project identified 'claude-code-base-action' @ 2.0.0 (npm) as malicious.
It is considered malicious because:
- The package communicates with a domain associated with malicious activity.
Malicious versions
Indicators of compromise (SHA-256)
Detection & response playbook
Malicious packageFind it
Search your lockfiles and build artifacts for claude-code-base-action (2 malicious versions).
If you installed it — respond
Remove claude-code-base-action 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 claude-code-base-action 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
Credits
- Amazon Inspector · finder
- OpenSSF: Package Analysis · finder
Detect & block this
O3 blocks claude-code-base-action-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.