GHSA-4r4f-gg25-rmg5 plone.app.textfield: Stored XSS by spoofing mime type

• PyPI plone.app.textfield: < 2.0.2 → fixed in 2.0.2 • PyPI plone.app.textfield: >= 3.0.0, < 3.0.2 → fixed in 3.0.2 • PyPI plone.app.textfield: >= 4.0.0, < 4.0.1 → fixed in 4.0.1

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.