CVE-2025-41253: Spring Cloud Gateway Info Disclosure Bug

CVE-2025-41253 Overview

CVE-2025-41253 is an Expression Language Injection vulnerability affecting Spring Cloud Gateway Server Webflux that enables attackers to expose sensitive environment variables and system properties. This vulnerability leverages Spring Expression Language (SpEL) through improperly secured actuator endpoints, allowing unauthorized access to critical application configuration data.

An application is considered vulnerable when all of the following conditions are met:

• The application uses Spring Cloud Gateway Server Webflux (Spring Cloud Gateway Server WebMVC is not affected)
• An admin or untrusted third party uses SpEL to access environment variables or system properties via routes
• The Spring Cloud Gateway Server Webflux actuator web endpoint is enabled via management.endpoints.web.exposure.include=gateway and management.endpoint.gateway.enabled=true or management.endpoint.gateway.access=unrestricted
• The actuator endpoints are accessible to attackers and remain unsecured

Critical Impact

Unauthorized disclosure of sensitive environment variables and system properties, including potential exposure of credentials, API keys, and internal configuration details through SpEL injection.

Affected Products

• Spring Cloud Gateway Server Webflux (vulnerable versions with exposed actuator endpoints)

Discovery Timeline

• 2025-10-16 - CVE-2025-41253 published to NVD
• 2025-10-16 - Last updated in NVD database

Technical Details for CVE-2025-41253

Vulnerability Analysis

This vulnerability is classified under CWE-917 (Improper Neutralization of Special Elements used in an Expression Language Statement), commonly known as Expression Language Injection. The flaw exists in how Spring Cloud Gateway Server Webflux processes route configurations that contain SpEL expressions.

When actuator endpoints are enabled and left unsecured, attackers can craft malicious routes that leverage SpEL expressions to extract sensitive information from the application's runtime environment. This information disclosure can reveal database credentials, API secrets, internal service URLs, and other confidential configuration parameters that could facilitate further attacks.

The network-accessible nature of this vulnerability means that any attacker who can reach the actuator endpoints can potentially exploit this flaw without requiring authentication. The impact is primarily confidentiality-focused, as the vulnerability enables information extraction rather than direct modification or disruption.

Root Cause

The root cause lies in improper access controls on Spring Cloud Gateway's actuator endpoints combined with the powerful capabilities of SpEL. When administrators expose the gateway actuator endpoint without proper authentication and authorization, the SpEL evaluation engine can be abused to access system properties and environment variables. The application fails to adequately restrict which expressions can be evaluated and what data they can access.

Attack Vector

This vulnerability is exploitable over the network without requiring user interaction or authentication. An attacker can exploit this vulnerability by:

1. Identifying exposed Spring Cloud Gateway actuator endpoints
2. Creating or modifying routes through the gateway actuator API
3. Injecting SpEL expressions within route configurations that reference environment variables or system properties
4. Extracting sensitive data returned from the SpEL evaluation

The attack targets the /actuator/gateway endpoint when it is improperly secured, allowing route manipulation that includes malicious SpEL expressions designed to leak sensitive information.

Detection Methods for CVE-2025-41253

Indicators of Compromise

• Unusual HTTP requests targeting /actuator/gateway or related actuator endpoints from external IP addresses
• Route configurations containing SpEL expressions referencing systemProperties or systemEnvironment
• Unexpected modifications to gateway routes via the actuator API
• Access logs showing attempts to enumerate or access actuator endpoints

Detection Strategies

• Monitor web application logs for requests to actuator endpoints, particularly /actuator/gateway/routes and /actuator/gateway/refresh
• Implement application-level logging to capture route creation and modification events
• Deploy web application firewalls (WAF) with rules to detect SpEL injection patterns in request payloads
• Use SentinelOne Singularity to monitor for anomalous process behavior and unexpected environment variable access patterns

Monitoring Recommendations

• Enable audit logging for all actuator endpoint access attempts
• Configure alerting for any route modifications through the gateway actuator
• Implement network monitoring to detect reconnaissance activity against management endpoints
• Review application configurations periodically to ensure actuator endpoints maintain proper security controls

How to Mitigate CVE-2025-41253

Immediate Actions Required

• Disable the gateway actuator endpoint if not required by setting management.endpoint.gateway.enabled=false
• Remove gateway from management.endpoints.web.exposure.include to prevent external access
• Implement Spring Security to require authentication and authorization for all actuator endpoints
• Restrict network access to actuator endpoints using firewall rules or network segmentation
• Review existing route configurations for potentially malicious SpEL expressions

Patch Information

Consult the Spring Security Advisory for CVE-2025-41253 for official patch information and recommended upgrade paths. Apply vendor-provided security updates as soon as they become available.

Workarounds

• Set management.endpoint.gateway.enabled=false to completely disable the gateway actuator endpoint
• Configure actuator endpoint access to require authentication: management.endpoints.web.exposure.include= (empty value to disable all web exposure)
• Implement IP-based access controls to restrict actuator access to trusted management networks only
• Use Spring Security's @PreAuthorize or similar mechanisms to enforce role-based access to sensitive endpoints

# Configuration example - securing actuator endpoints in application.properties
management.endpoint.gateway.enabled=false
management.endpoints.web.exposure.include=health,info
management.endpoints.web.exposure.exclude=gateway,env,configprops