Which versions of markdownlint-cli2-action are malicious?

Every published version of markdownlint-cli2-action on npm is considered malicious. Remove the package entirely.

How do I remediate markdownlint-cli2-action if I installed it?

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.

I already installed markdownlint-cli2-action — how do I know if it already compromised me?

If markdownlint-cli2-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.

How do I find markdownlint-cli2-action across my projects, lockfiles, and CI pipelines?

Search your lockfiles and build artifacts for markdownlint-cli2-action (all published versions).

Malicious package

markdownlint-cli2-actionnpm

Advisory published Dec 1, 2025Updated Dec 1, 2025

markdownlint-cli2-action is a confirmed malicious npm package (MAL-2025-191516) that executes malicious code on install. Do not install it — remove it immediately and rotate any exposed credentials.

Malicious code in markdownlint-cli2-action (npm)

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

Find it
Search your lockfiles and build artifacts for markdownlint-cli2-action (all published versions).
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.
Did it already run?
If markdownlint-cli2-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

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.

Malware detection Runtime egress monitoring

Explore

All malware advisories How O3 detects malware Vulnerability database