CVE-2025-41243 is a critical security vulnerability identified in Spring Cloud Gateway Server Webflux, a reactive API gateway framework widely used in microservices architectures. The vulnerability stems from improper neutralization of special elements used in Expression Language (EL) statements, classified under CWE-917 (Improper Neutralization of Special Elements used in an Expression Language Statement) and CWE-94 (Improper Control of Generation of Code). This flaw allows an attacker to manipulate Spring Environment properties via the actuator endpoints exposed by Spring Boot when certain conditions are met. Specifically, the vulnerability is exploitable only if the application uses Spring Cloud Gateway Server Webflux (not the WebMVC variant), includes Spring Boot actuator as a dependency, has the gateway actuator endpoint enabled through management.endpoints.web.exposure.include=gateway, and if these actuator endpoints are accessible and unsecured to attackers. Exploitation requires no authentication or user interaction, enabling remote attackers to execute arbitrary code or modify environment properties, leading to full compromise of the affected system. The CVSS v3.1 base score is 10.0, indicating maximum severity with network attack vector, low attack complexity, no privileges required, no user interaction, and complete impact on confidentiality, integrity, and availability. Affected versions include Spring Cloud Gateway 3.1.x, 4.0.x, 4.1.x, 4.2.x, and 4.3.x. Although no public exploits are currently known in the wild, the critical nature and ease of exploitation make this a high-priority threat for organizations using these versions. The vulnerability highlights the risks of exposing actuator endpoints without proper security controls, especially in reactive gateway environments where EL injection can lead to remote code execution or environment manipulation.

For European organizations, the impact of CVE-2025-41243 is significant due to the widespread adoption of Spring Cloud Gateway in cloud-native and microservices deployments across industries such as finance, telecommunications, healthcare, and government services. Successful exploitation can lead to complete system compromise, data breaches, service disruption, and potential lateral movement within internal networks. Confidentiality is at risk as attackers can access sensitive configuration and environment data. Integrity is compromised through unauthorized modification of application properties or code execution, potentially leading to fraudulent transactions or data tampering. Availability can be disrupted by attackers causing denial-of-service or system instability. Given the criticality and ease of exploitation without authentication, attackers can rapidly compromise vulnerable systems, making this a severe threat to European enterprises relying on Spring Cloud Gateway for API management and routing. The exposure of actuator endpoints without authentication is a common misconfiguration, increasing the likelihood of exploitation. Additionally, regulatory frameworks such as GDPR impose strict requirements on data protection, and breaches resulting from this vulnerability could lead to substantial legal and financial penalties for European organizations.

To mitigate CVE-2025-41243 effectively, European organizations should: 1) Immediately audit all Spring Cloud Gateway deployments to identify usage of affected versions (3.1.x through 4.3.x) and verify if the Webflux variant is in use. 2) Disable or restrict access to the gateway actuator endpoints by removing 'gateway' from management.endpoints.web.exposure.include or by explicitly securing actuator endpoints with strong authentication and authorization mechanisms such as OAuth2, LDAP, or mutual TLS. 3) Implement network-level controls such as firewall rules or API gateways to restrict actuator endpoint access to trusted internal networks only. 4) Upgrade Spring Cloud Gateway to the latest patched versions once available from the vendor, as no patches are currently linked but should be prioritized upon release. 5) Conduct thorough code and configuration reviews to ensure no other EL injection vectors exist and validate input sanitization practices. 6) Monitor logs and network traffic for unusual access patterns to actuator endpoints and signs of exploitation attempts. 7) Employ runtime application self-protection (RASP) or Web Application Firewalls (WAF) capable of detecting and blocking EL injection payloads. 8) Educate development and operations teams about the risks of exposing actuator endpoints without security and enforce secure defaults in deployment pipelines.