CVE-2025-41243: 
Java vulnerability analysis and mitigation

A critical vulnerability (CVE-2025-41243) was discovered in Spring Cloud Gateway Server WebFlux, disclosed on September 8, 2025. The vulnerability allows attackers to modify Spring Environment properties through the Spring Expression Language when specific conditions are met. This flaw affects Spring Cloud Gateway versions ranging from 3.1.0 through 4.3.x, with a maximum CVSS score of 10.0 (Spring Advisory, Security Online).

The vulnerability is triggered when all of the following conditions are present: the application uses Spring Cloud Gateway Server WebFlux (Spring Cloud Gateway Server WebMVC is not affected), Spring Boot actuator is included as a dependency, the Gateway Server WebFlux actuator web endpoint is enabled via management.endpoints.web.exposure.include=gateway, and the actuator endpoints are both available and unsecured. The flaw has been assigned a CVSS score of 10.0, indicating the highest possible severity level (Spring Advisory).

When successfully exploited, this vulnerability allows attackers to manipulate sensitive Spring Environment properties, potentially compromising application behavior. Given that Spring Cloud Gateway is commonly deployed in microservices architectures as a reactive API gateway at enterprise network edges, the impact could be particularly severe when actuator endpoints are exposed without proper security controls (Security Online).

Spring has released patched versions: 4.3.1 (OSS) for 4.3.x, 4.2.5 (OSS) for 4.2.x, 4.1.11 (Enterprise) for 4.1.x, and 3.1.11 (Enterprise) for 3.1.x users. For those unable to upgrade immediately, alternative mitigations include removing 'gateway' from the management.endpoints.web.exposure.include property or implementing proper security controls for actuator endpoints (Spring Advisory).

The vulnerability was responsibly reported by security researcher Ezzer17. The critical nature of the vulnerability and its maximum CVSS score has drawn significant attention in the security community, particularly given Spring Cloud Gateway's widespread use in enterprise environments (Spring Advisory).