Versions of the package web3-utils before 4.2.1 are vulnerable to Prototype Pollution via the utility functions format and mergeDeep, due to insecure recursive merge. An attacker can manipulate an object's prototype, potentially leading to the alteration of the behavior of all objects inheriting from the affected prototype by passing specially crafted input to these functions.
https://security.snyk.io/vuln/SNYK-JS-WEB3UTILS-6229337
https://github.com/web3/web3.js/commit/8ed041c6635d807b3da8960ad49e125e3d1b0e80