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Malicious package

web-vitals-polyfill-core-v1npm

Advisory published Updated

web-vitals-polyfill-core-v1 is a confirmed malicious npm package (MAL-2026-17303) that typosquats a legitimate package to trick installs (malicious version 1.0.0). Do not install it — remove it immediately and rotate any exposed credentials.

Malicious code in web-vitals-polyfill-core-v1 (npm)

MAL-2026-17303
Immediate action
Remove the package, then rotate any secrets the build/runtime could reach.
npm uninstall web-vitals-polyfill-core-v1

What this malware does

The package name mimics the widely-used web-vitals polyfill but the tarball ships disk/index.min.js, a base64-wrapped service-worker payload (self.PWA_ROUTER.executeTacticalRouting) that resolves an active destination via DoH TXT lookups of api.chinazhangsan.ccwu.cc (queried through doh.pub and dns.alidns.com) with base64-encoded fallback endpoints on gist.githubusercontent.com/chinazhangsan999-crypto and api.npoint.io, performs decoy fetches, and issues Response.redirect(targetUrl, 302) to the resolved host. package.json declares main: index.js which is not present in the tarball, so the package has no legitimate library surface; its shipped code is exclusively the obfuscated redirector, intended to be loaded into a consuming site's service worker where it can hijack end-user navigation to attacker-chosen destinations resolved at runtime through multi-provider DNS-over-HTTPS and paste-site fallbacks.

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

1 flagged
1.0.0

Indicators of compromise (SHA-256)

38311c0f483e9485a7b5e8aa7f9a093a40203d8e1a025c0bf5850c2874cffdfa
583291fe7133304271006d1ca425c04aebce7279be07963310434403dfc19319

Detection & response playbook

Typosquat
  1. Find it

    Search your lockfiles and build artifacts for web-vitals-polyfill-core-v1 (version 1.0.0).

  2. If you installed it — respond

    web-vitals-polyfill-core-v1 is a typosquat — you almost certainly intended a legitimately-named package. Remove web-vitals-polyfill-core-v1, install the correct package, and rotate any secrets exposed during the install since post-install scripts may have already run.

  3. Did it already run?

    If web-vitals-polyfill-core-v1 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. web-vitals-polyfill-core-v1 on npm has been identified as a malicious package (version 1.0.0 flagged). It should be removed immediately — do not install or keep it in your dependency tree.

Campaign

IN-MAL-2026-020749GHSA-h475-44q2-vfjx

References

Credits

  • Amazon Inspector · finder

Detect & block this

O3 blocks web-vitals-polyfill-core-v1-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.

Explore

web-vitals-polyfill-core-v1 (npm) malicious package — MAL-2026-17303 | O3 Security