Tandoor Recipes is an application for managing recipes, planning meals, and building shopping lists. Prior to 2.6.4, Tandoor Recipes allows authenticated users to inject arbitrary <style> tags into recipe step instructions. The bleach.clean() sanitizer explicitly whitelists the <style> tag, causing the backend to persist and serve unsanitized CSS payloads via the API. Any client consuming instructions_markdown from the API and rendering it as HTML without additional sanitization will execute attacker-controlled CSS — enabling UI redressing, phishing overlays, visual defacement, and CSS-based data exfiltration. This vulnerability is fixed in 2.6.4.