Sand Security researchers disclosed ‘WriteOut,’ a critical session-isolation flaw in Writer’s enterprise AI agent platform. By sending a link to a live agent preview, an attacker could get a victim’s session cookie forwarded into the attacker’s sandbox the moment it was opened — without the two needing to share an organization. The stolen token could expose private chats, documents, agent configurations, connectors, and LLM credentials, and in some cases grant administrative control. The flaw has since been fixed.