Agentless MFA is multi-factor authentication that protects an application without installing software directly on that app or server. Instead, the control is enforced through a proxy, gateway, identity provider, federation flow, or network-layer integration. This is useful for legacy and third-party applications that cannot easily be modified but still need stronger sign-in protection.
In cyber security, agentless MFA matters because it extends coverage to systems that would otherwise remain outside the MFA perimeter. Attackers often target those gaps with password stuffing, phishing, or reuse of stolen credentials. When deployed well, agentless MFA can block a login before the application ever sees the session. Defenders use it to add policy control, step-up authentication, and logging across mixed environments, while avoiding the cost and risk of app code changes.