n8n before 1.123.83, 2.41.4, and 2.42.1 Stored XSS via Chat Trigger customCss Parameter

n8n before 1.123.83, 2.x before 2.41.4, and 2.42.x before 2.42.1 contains a stored cross-site scripting vulnerability in the Chat Trigger hosted-chat page, where insufficiently sanitised customCss values are interpolated into the page as markup. Workflow authors can publish a chat without n8n user authentication whose payload executes on the instance origin, acting on the sessions of signed-in visitors.