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Malicious package

claude-code-base-actionnpm

Malicious code in claude-code-base-action (npm) Remove it immediately and rotate any exposed credentials.

MAL-2026-3811
Immediate action
Remove the package, then rotate any secrets the build/runtime could reach.
npm uninstall claude-code-base-action

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

2 flagged
2.0.02.2.2

Indicators of compromise (SHA-256)

f08c76c834d5f7c2ce735d4dd85684ec34f3dcc29e1353dc7633fb72ee79aaaf
3c9e36883f6e538eda86eb64854165d767b96458a12405a7ccd967c8015f6269
3000eab5b77e9247ae3dc1125384eaeb03ecdae7ecd17fe30ee6216a6a87c686

Detection & response playbook

Malicious package
  1. Find it

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

  2. 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.

  3. Did it already run?

    If claude-code-base-action 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.

  4. How O3 protects you

    O3 blocks claude-code-base-action 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. claude-code-base-action on npm has been identified as a malicious package (versions 2.0.0, 2.2.2 flagged). It should be removed immediately — do not install or keep it in your dependency tree.

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.

claude-code-base-action (npm) malicious package — MAL-2026-3811 | O3 Security