A XSS vulnerability exists in the getTip() method of Action Columns.
The Ext JS framework brings no built-in XSS protection, meaning that
developers are responsible for sanitizing their output. However. the method
above takes HTML-escaped data and un-escapes it. Therefore if the tooltip
contains user-controlled data a XSS is possible.
A fiddle demonstrating the issue can be found here:
The vendor tracked this issue with the internal ID EXTJS-26864.
MITRE assigned CVE-2018-8046 to this issue.
This issue has been fixed in version 6.6.0, the release notes are available