The reported security threat involves a novel Server-Side Request Forgery (SSRF) technique that leverages HTTP redirect loops to bypass traditional SSRF protections. SSRF vulnerabilities occur when an attacker can manipulate a server to make unintended HTTP requests, potentially accessing internal systems or sensitive data. This new technique exploits the behavior of HTTP redirect responses (3xx status codes) by chaining multiple redirects in a loop, causing the server to repeatedly follow redirects. By doing so, attackers can circumvent common SSRF mitigations that validate or restrict direct URLs by obfuscating the final destination through multiple redirects. This method can enable attackers to reach internal or protected endpoints that would otherwise be inaccessible due to URL filtering or allowlists. The technique was recently disclosed on the Reddit NetSec community and documented on slcyber.io, indicating it is a fresh discovery with limited public discussion and no known exploits in the wild at this time. The lack of affected versions or specific vulnerable products suggests this is a generic technique applicable to any web application or service that performs server-side HTTP requests without robust redirect handling. The threat highlights a subtle but impactful vector for SSRF exploitation, emphasizing the need for careful validation of redirect chains and final resolved URLs rather than just initial request URLs.

For European organizations, this SSRF technique poses a significant risk, especially for enterprises relying on web applications that perform server-side HTTP requests to internal services, APIs, or cloud metadata endpoints. Successful exploitation can lead to unauthorized access to internal networks, exposure of sensitive data, or pivoting attacks within corporate infrastructure. Critical sectors such as finance, healthcare, telecommunications, and government services in Europe often use complex web architectures with internal microservices and cloud environments, making them potential targets. The ability to bypass SSRF protections via redirect loops increases the attack surface and complicates detection and prevention. While no active exploits are currently known, the technique's novelty and evasion capabilities mean that attackers could adopt it rapidly, potentially leading to data breaches or service disruptions. The medium severity rating reflects the moderate difficulty of exploitation combined with potentially high impact if internal systems are accessed. European organizations with strict data protection regulations (e.g., GDPR) face additional compliance risks if such vulnerabilities lead to data leaks.

To mitigate this SSRF technique, European organizations should implement the following specific measures: 1) Enforce strict validation of the entire redirect chain by resolving all HTTP redirects server-side before allowing the request, ensuring the final destination URL is within an approved allowlist or safe domain. 2) Limit or disable automatic following of HTTP redirects in server-side HTTP clients where possible, or set a maximum redirect count to prevent loops. 3) Employ network segmentation and firewall rules to restrict server-side HTTP requests to only necessary internal services, reducing the impact of SSRF. 4) Use metadata service access tokens or cloud provider-specific protections to prevent unauthorized internal API access. 5) Monitor and log server-side HTTP requests and redirect behaviors to detect unusual patterns indicative of redirect loop exploitation. 6) Conduct regular security assessments and penetration testing focusing on SSRF vectors, including redirect handling. 7) Educate development teams about the risks of SSRF and the importance of validating final resolved URLs rather than just initial input URLs. These targeted actions go beyond generic SSRF advice by focusing on redirect loop handling and comprehensive URL resolution.