EspoCRM 5.6.4 is vulnerable to user password hash enumeration. A malicious authenticated attacker can brute-force a user password hash by 1 symbol at a time using specially crafted api/v1/User?filterList filters.

EspoCRM 5.6.4 is vulnerable to stored XSS due to lack of filtration of user-supplied data in the Knowledge base. A malicious attacker can inject JavaScript code in the body parameter during api/v1/KnowledgeBaseArticle knowledge-base record creation.

EspoCRM version 5.6.4 is vulnerable to stored XSS due to lack of filtration of user-supplied data in the api/v1/Document functionality for storing documents in the account tab. An attacker can upload a crafted file that contains JavaScript code in its name. This code will be executed when a user opens a page of any profile with this.