SuiteCRM vulnerable to authenticated SSRF via PDF export

SuiteCRM is an open-source, enterprise-ready Customer Relationship Management (CRM) software application. Prior to versions 7.15.1 and 8.9.3, it is possible to create PDF templates with `<img>` tags. When a PDF is exported using this template, the content (for example, `<img src=http://{burp_collaborator_url}>` is rendered server side, and thus a request is issued from the server, resulting in Server-Side Request Forgery. Versions 7.15.1 and 8.9.3 patch the issue.