Eilonc-Pillar

A second-order expression injection issue exists in the Form nodes of this open source workflow automation platform. An unauthenticated attacker can inject and evaluate arbitrary expressions by submitting crafted form data. This occurs when a form node interpolates a value provided by an unauthenticated user and the field value begins with an `=` character, triggering a double-evaluation of the content. While the injection is initially limited to data within the expression context, it can escalate to remote code execution on the host if chained with an expression sandbox escape. Exploitation requires a specific workflow configuration where user input is reflected back, such as on a confirmation page.

n8n is an open-source workflow automation platform. An authenticated user with permission to create or modify workflows can exploit crafted expressions in workflow parameters to trigger system command execution on the host running n8n. This allows for potential full server compromise, including the theft of API keys, credentials, and secrets. The issue stems from an expression escape vulnerability and incomplete AST-based sanitization. Public exploits are available.