Which versions of importmap-polyfil are malicious?

Every published version of importmap-polyfil on npm is considered malicious. Remove the package entirely.

How do I remediate importmap-polyfil if I installed it?

Remove importmap-polyfil 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 importmap-polyfil — how do I know if it already compromised me?

If importmap-polyfil 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.

Is importmap-polyfil part of a known attack campaign?

Yes — importmap-polyfil is associated with the GHSA-m365-ph8h-jmwf 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 importmap-polyfil across my projects, lockfiles, and CI pipelines?

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

Malicious package

importmap-polyfilnpm

Malicious code in importmap-polyfil (npm) Remove it immediately and rotate any exposed credentials.

MAL-2026-89

Immediate action

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

npm uninstall importmap-polyfil

What this malware does

The package importmap-polyfil 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.

Malicious versions

all versions

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

Indicators of compromise (SHA-256)

160cd55bcb6743ced21e89220ffdb7a2d8fa0ab01cd979815a3108b558be55aa

d2d874c3ab0f1a1f131dca5c54020df385d3d3a2d8a58490de33ab3ebe3cf797

Detection & response playbook

Malicious package

Find it
Scan your lockfiles (package-lock.json, pnpm-lock.yaml, yarn.lock, requirements.txt, poetry.lock, etc.) and build artifacts for importmap-polyfil (all published versions). O3 Security's supply-chain scanner checks every dependency against known-malicious package intelligence at install time and in CI, flagging importmap-polyfil across your stack and pipelines.
If you installed it — respond
Remove importmap-polyfil 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 importmap-polyfil 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.
How O3 protects you
O3 blocks importmap-polyfil 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. importmap-polyfil 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.

Campaign

GHSA-m365-ph8h-jmwf

References

github.com

Credits

Amazon Inspector · finder

Detect & block this

O3 blocks importmap-polyfil-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