Zimbra Collaboration Suite before 8.6 patch 13, 8.7.x before 8.7.11 patch 10, and 8.8.x before 8.8.10 patch 7 or 8.8.x before 8.8.11 patch 3 allows SSRF via the ProxyServlet component.
packetstormsecurity.com/files/152487/Zimbra-Collaboration-Autodiscover-Servlet-XXE-ProxyServlet-SSRF.html
packetstormsecurity.com/files/153190/Zimbra-XML-Injection-Server-Side-Request-Forgery.html
www.rapid7.com/db/modules/exploit/linux/http/zimbra_xxe_rce
blog.tint0.com/2019/03/a-saga-of-code-executions-on-zimbra.html
blog.zimbra.com/2019/03/9826/
bugzilla.zimbra.com/show_bug.cgi?id=109127
wiki.zimbra.com/wiki/Security_Center
wiki.zimbra.com/wiki/Zimbra_Security_Advisories
www.exploit-db.com/exploits/46693/