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 equals it bypasses the safe_html transform entirely on render. The transform itself is sound — it correctly strips "on*" event-handler attributes and "javascript:/data:" URIs; the defect is that it is never invoked for these values. The unsanitized value is then emitted via "tal:content="structure ..."", which performs no escaping, so the payload executes in the viewer's browser. This can be a problem when a RichText field is wrongly defined in code with a "mimeType" and "outputMimeType" that are the same, or when the REST API is used to the same effect. Patches The problem has been patched: * For Plone 6.0, upgrade "plone.app.textfield" to 2.0.2. * For Plone 6.1, upgrade "plone.app.textfield" to 3.0.2. * For Plone 6.2, upgrade "plone.app.textfield" to 4.0.1. Workarounds There is no known workaround.