html-to-gutenbergnpm
Advisory published Updated
html-to-gutenberg is a confirmed malicious npm package (MAL-2026-6359) that executes malicious code on install (malicious versions 4.2.11, 4.2.12, 4.2.13…). Do not install it — remove it immediately and rotate any exposed credentials.
Malicious code in html-to-gutenberg (npm)
What this malware does
The published tarball contains api.js at the package root, a heavily obfuscated loader using an obfuscator.io-style XOR-decoded string table (key 0x46) that reconstructs identifiers including 'constructor', stashes require and module on the global object, and uses Function(...) to compile and immediately invoke an approximately 9.6 KB decoded payload. The file is referenced only by the author's manual scripts.build step (node api.js && tsc); it is not referenced by the package's main entry (index.js), not imported by any reachable module, and not invoked by the declared postinstall. The postinstall script performs a local file-copy of vendor/fetch-page-assets/index.ts into node_modules via fs.copyFileSync with no network I/O and no shell exec of api.js. Because the obfuscated loader is dormant on both npm install and require of the package, no installer-harm dataflow is produced in normal consumer use, but shipping an obfuscated dynamic-eval loader with concealed payload contents in a published tarball is an unusual transparency and supply-chain hygiene concern.
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
Indicators of compromise (SHA-256)
Detection & response playbook
Malicious packageFind it
Search your lockfiles and build artifacts for html-to-gutenberg (15 malicious versions).
If you installed it — respond
Remove html-to-gutenberg 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 html-to-gutenberg 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
Campaign
References
Credits
- Amazon Inspector · finder
Detect & block this
O3 blocks html-to-gutenberg-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.