CVE-2025-41235 in Spring Cloud Gateway
Summary
by MITRE • 05/30/2025
Spring Cloud Gateway Server forwards the X-Forwarded-For and Forwarded headers from untrusted proxies.
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Analysis
by VulDB Data Team • 05/30/2025
Spring Cloud Gateway Server represents a critical vulnerability in network infrastructure security where the system fails to properly validate and sanitize forwarded headers from untrusted sources. This vulnerability specifically affects the X-Forwarded-For and Forwarded headers that are commonly used in proxy configurations to preserve client IP addresses through multiple layers of network intermediaries. The flaw stems from insufficient input validation mechanisms that allow malicious actors to inject forged header values, potentially compromising the integrity of client identity information within distributed systems.
The technical implementation of this vulnerability occurs at the gateway level where Spring Cloud Gateway processes incoming requests and forwards them to backend services. When untrusted proxies submit X-Forwarded-For or Forwarded headers, the system accepts these values without proper verification of their authenticity or source legitimacy. This creates a potential attack vector where adversaries can manipulate the header values to either mask their true IP addresses or impersonate legitimate clients within the network infrastructure. The vulnerability directly aligns with CWE-20, which addresses improper input validation, and represents a significant weakness in the principle of least privilege within network security architectures.
Operational impacts of this vulnerability extend beyond simple IP address spoofing to encompass broader security implications for access control and audit logging systems. When malicious actors manipulate forwarded headers, they can potentially bypass IP-based access controls, gain unauthorized access to protected resources, or disrupt normal network monitoring and logging procedures. The vulnerability undermines the trust model that organizations rely upon when implementing proxy-based architectures, as it allows attackers to forge client identity information that may be used for authentication decisions or security policy enforcement. This issue particularly affects environments where backend services make security decisions based on client IP addresses or forwarded header information, creating potential escalation paths for privilege escalation attacks.
Mitigation strategies for this vulnerability must address both immediate defensive measures and long-term architectural improvements to prevent header manipulation attacks. Organizations should implement strict header validation policies that verify the authenticity of forwarded headers through cryptographic means or by maintaining trusted proxy lists. The recommended approach includes configuring Spring Cloud Gateway to either strip or validate forwarded headers before processing requests, ensuring that only headers from trusted proxy sources are accepted. Security controls should be implemented in accordance with the ATT&CK framework's T1566 technique for Phishing with Spoofed Client Certificates, as the vulnerability enables similar spoofing capabilities. Network administrators should also consider implementing additional layers of security monitoring to detect anomalous header patterns and establish automated alerting for suspicious forwarded header manipulations.