The Five9 Live Chat plugin for WordPress suffers from a stored XSS vulnerability due to insufficient sanitization and escaping of the 'toolbar' attribute in the [five9-chat] shortcode. This allows authenticated users with contributor or higher privileges to inject arbitrary JavaScript code into pages. When other users access these pages, the injected scripts execute, potentially leading to session hijacking or other client-side attacks. The vulnerability affects all versions up to and including 1.1.2. There is no indication of known exploits in the wild or an official patch at this time.

Successful exploitation allows authenticated contributors or higher to inject persistent malicious scripts into pages, which execute in the context of users viewing those pages. This can lead to information disclosure or user session compromise. The vulnerability does not affect availability and requires user interaction (viewing the injected page). The CVSS score of 6.4 reflects a medium severity with network attack vector, low attack complexity, and no user interaction required for the script execution once injected.

Patch status is not yet confirmed — check the vendor advisory for current remediation guidance. Until an official fix is released, restrict contributor-level access to trusted users only and consider disabling or removing the Five9 Live Chat plugin if possible. Monitor for plugin updates from Five9 that address this vulnerability.