Zimbra Collaboration Suite phone cross-site scripting vulnerability

Synacor Zimbra Collaboration Suite (ZCS) is an open source collaboration suite from Synacor, Inc. A cross-site scripting vulnerability exists in Zimbra Collaboration Suite version 8.8.15, which stems from the lack of effective filtering and escaping of user-supplied data in the phone parameter of /h/search?action=voicemail & action=listen, which could be exploited to execute arbitrary JavaScript.