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Malicious package

markdownlint-cli2-actionnpm

Malicious code in markdownlint-cli2-action (npm) Remove it immediately and rotate any exposed credentials.

MAL-2025-191516
Immediate action
Remove the package, then rotate any secrets the build/runtime could reach.
npm uninstall markdownlint-cli2-action

What this malware does

The package markdownlint-cli2-action was found to contain malicious code.

Malicious versions

all versions

Every published version of this package is considered malicious — remove it entirely.

Indicators of compromise (SHA-256)

655d6053e439a95c848bd57cd41cba21de94f230903346b885b527082e131915

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 markdownlint-cli2-action (all published versions). O3 Security's supply-chain scanner checks every dependency against known-malicious package intelligence at install time and in CI, flagging markdownlint-cli2-action across your stack and pipelines.

  2. If you installed it — respond

    Remove markdownlint-cli2-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 markdownlint-cli2-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 markdownlint-cli2-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. markdownlint-cli2-action on npm has been identified as a malicious package (all published versions flagged). It should be removed immediately — do not install or keep it in your dependency tree.

Credits

  • Amazon Inspector · finder

Detect & block this

O3 blocks markdownlint-cli2-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.

markdownlint-cli2-action (npm) malicious package — MAL-2025-191516 | O3 Security