convict vulnerable to Prototype Pollution

Improperly Controlled Modification of Object Prototype Attributes ('Prototype Pollution') vulnerability in Mozilla Convict. This allows an attacker to inject attributes that are used in other components, or to override existing attributes with ones that have incompatible type, which may lead to a crash. The main use case of Convict is for handling server-side configurations written by the admins owning the servers, and not random users. So it's unlikely that an admin would deliberately sabotage their own server. Still, a situation can happen where an admin not knowledgeable about JavaScript could be tricked by an attacker into writing the malicious JavaScript code into some config files. This issue affects Convict: before 6.2.4.