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.
https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2019-9621
https://wiki.zimbra.com/wiki/Zimbra_Security_Advisories
https://wiki.zimbra.com/wiki/Security_Center
https://bugzilla.zimbra.com/show_bug.cgi?id=109127
https://blog.zimbra.com/2019/03/9826/
http://packetstormsecurity.com/files/153190/Zimbra-XML-Injection-Server-Side-Request-Forgery.html