Zammad: Missing authorization in GraphQL mutation for suggesting knowledge base answers

Zammad is a web based open source helpdesk/customer support system. Prior to 7.0.2, an authorization bypass vulnerability was found that allows an authenticated agent to read knowledge base answer content they should not be able to access. The vulnerable GraphQL mutation is meant to transform a knowledge base answer suggestion so it can be inserted into the ticket editor, but it only checks if the user has the ticket.agent permission. Checking the authorization to the knowledge base answer itself is missing. This vulnerability is fixed in 7.0.2.