GHSA-8RQH-VXPR-X77P plone.restapi: Stored XSS by spoofing mime type

Impact A stored XSS affecting RichText fields. RichTextValue.output returns the raw, unsanitized stored value whenever the stored mimeType equals the outputMimeType. Because the safe-HTML output type text/x-html-safe is the type that signifies "already sanitized", any value whose stored mimeType...