GHSA-rhm7-7469-rcpw: Persistent Cross-site Scripting in eZ Platform Rich Text Field Type

The validator for the RichText fieldtype blocklists javascript: and vbscript: in links to prevent XSS. This can leave other options open, and the check can be circumvented using upper case. Content editing permissions for RichText content is required to exploit this vulnerability, which typically means Editor role or higher. The fix implements an allowlist instead, which allows only approved link protocols. The new check is case insensitive.