CVE-2026-33889: ApostropheCMS: Stored XSS via CSS Custom Property Injection in @apostrophecms/color-field Escaping Style Tag Context

The @apostrophecms/color-field module bypasses color validation for values prefixed with -- (intended for CSS custom properties), but performs no HTML sanitization on these values. When styles containing attacker-controlled color values are rendered into <style> tags — both in the global stylesheet (editors only) and in per-widget style elements (all visitors) — the lack of escaping allows an editor to inject </style> followed by arbitrary HTML/JavaScript, achieving stored XSS against all site visitors.