MAL-2026-17303 Malicious code in web-vitals-polyfill-core-v1 (npm)
- Package
- web-vitals-polyfill-core-v1
- Registry
- npm
What is MAL-2026-17303?
MAL-2026-17303 is a malicious package in web-vitals-polyfill-core-v1, published on 30 Sep 2026.
Official description
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.
What should I do about MAL-2026-17303?
Remove the package from your dependencies and lockfiles, then rotate any secrets on machines where it was installed.
Sources
Also known as GHSA-h475-44q2-vfjx.