Secure Custom Fields < 6.9.8 - Admin+ Stored XSS via HTML Attribute Name Injection into Field Definition

Description

The plugin does not sanitize a persisted field definition before emitting part of it as an HTML attribute name, allowing a user able to configure its fields to store a payload that executes as JavaScript in the browser of any user who views a page rendering the affected field, which on multisite lets a site administrator who lacks the unfiltered_html capability inject script into other users' sessions.