CVE-2022-45060 is a high-severity vulnerability affecting Varnish Cache versions 5.x and 6.x prior to 6.0.11, 7.x prior to 7.1.2, and 7.2.x prior to 7.2.1. The issue arises from improper handling of HTTP/2 pseudo-headers by the Varnish server. Specifically, an attacker can craft HTTP/2 requests containing pseudo-header characters that are invalid when translated into HTTP/1 request lines. Varnish, acting as a reverse proxy or caching server, converts incoming HTTP/2 requests into HTTP/1 requests for backend servers. Due to insufficient validation, these malformed pseudo-headers cause Varnish to generate invalid HTTP/1 requests to backend servers. This HTTP Request Forgery can be exploited to manipulate backend servers into processing malicious requests, potentially triggering vulnerabilities on those backend systems. The vulnerability is rooted in CWE-20 (Improper Input Validation), indicating that Varnish does not adequately sanitize or validate input before forwarding it. The CVSS 3.1 base score is 7.5 (high), reflecting the network attack vector, low attack complexity, no privileges or user interaction required, and a significant impact on integrity but no impact on confidentiality or availability. No known exploits are reported in the wild as of the publication date. The vulnerability affects multiple major Varnish Cache versions, including the long-term support 6.0.x series, emphasizing the importance of patching. Since Varnish is widely used as a caching and reverse proxy server to accelerate web applications, this vulnerability can be leveraged to bypass security controls or exploit backend server vulnerabilities indirectly, making it a critical concern for organizations relying on Varnish in their web infrastructure.

For European organizations, the impact of CVE-2022-45060 can be significant, especially for those deploying Varnish Cache as part of their web delivery stack. The vulnerability allows attackers to craft malicious HTTP/2 requests that cause Varnish to forward malformed HTTP/1 requests to backend servers. This can lead to exploitation of backend vulnerabilities, unauthorized request forgery, or manipulation of backend application logic. The integrity of backend systems is at risk, potentially enabling attackers to perform unauthorized actions or escalate privileges indirectly. While confidentiality and availability are not directly impacted by this vulnerability, the compromise of backend systems can lead to data integrity issues, unauthorized data modification, or further chained attacks. European organizations in sectors such as finance, e-commerce, government, and critical infrastructure that rely on Varnish for performance and security could face increased risk of targeted attacks. Additionally, the lack of authentication or user interaction requirements lowers the barrier for exploitation, increasing the threat landscape. The vulnerability also poses compliance risks under regulations like GDPR if backend systems are compromised, leading to potential data breaches or unauthorized data processing.

To mitigate CVE-2022-45060 effectively, European organizations should: 1) Immediately update Varnish Cache to the fixed versions: 6.0.11 or later for the 6.0.x LTS series, 7.1.2 or later for 7.1.x, and 7.2.1 or later for 7.2.x. 2) Implement strict input validation and filtering on the backend servers to ensure they do not process malformed or unexpected HTTP/1 requests, adding an additional layer of defense. 3) Deploy Web Application Firewalls (WAFs) or reverse proxies capable of detecting and blocking malformed HTTP/2 pseudo-headers or suspicious request patterns before they reach Varnish. 4) Monitor Varnish and backend server logs for unusual request patterns or errors indicative of malformed requests or attempted exploitation. 5) Conduct security assessments and penetration testing focusing on the interaction between Varnish and backend servers to identify potential chained vulnerabilities. 6) Where possible, segment backend servers behind additional security controls to limit the impact of any forged requests. 7) Maintain an up-to-date inventory of Varnish deployments and ensure patch management processes prioritize this vulnerability due to its high severity and wide impact. These steps go beyond generic advice by emphasizing backend validation, layered defenses, and proactive monitoring tailored to the nature of this vulnerability.