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 objects 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.
The product receives input from an upstream component that specifies attributes that are to be initialized or updated in an object, but it does not properly control modifications of attributes of the object prototype.