convict before 6.2.4 was discovered to contain a prototype pollution vulnerability. An attacker can inject attributes that are used in other components and can 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.