This indicates an attack attempt against a Remote Code Execution vulnerability in the Spring Cloud Gateway when the Gateway Actuator endpoint is enabled.
The vulnerability is caused by improper handling of a crafted HTTP request. A remote authenticated attacker may be able to exploit this to execute arbitrary remote code within the context of the application, via a crafted HTTP request.
Spring Cloud Gateway 3.1.0
Spring Cloud Gateway 3.0.0 to 3.0.6
System Compromise: Remote attackers can gain control of vulnerable systems.
Apply the most recent upgrade or patch from the vendor.