CVE-2021-28165 is a high-severity vulnerability affecting multiple versions of Eclipse Jetty, specifically versions 7.2.2 through 9.4.38, 10.0.0.alpha0 through 10.0.1, and 11.0.0.alpha0 through 11.0.1. Eclipse Jetty is a widely used open-source Java-based HTTP server and servlet container often embedded in applications and services to provide web server capabilities. The vulnerability is classified under CWE-400 (Uncontrolled Resource Consumption) and CWE-551 (Resource Exhaustion). The core issue arises when the server receives a large invalid TLS (Transport Layer Security) frame. Processing such a malformed TLS frame causes the Jetty server's CPU usage to spike to 100%, effectively leading to a denial-of-service (DoS) condition by exhausting CPU resources. This vulnerability does not require any authentication or user interaction, and can be exploited remotely over the network (CVSS vector AV:N/AC:L/PR:N/UI:N). The impact is limited to availability, with no direct confidentiality or integrity compromise. Although no known exploits have been reported in the wild, the ease of exploitation and the potential for service disruption make this a significant risk for systems relying on vulnerable Jetty versions for secure communications. No official patches are linked in the provided data, but upgrading to fixed versions or applying vendor-provided mitigations is implied. The vulnerability affects TLS handling, a critical component for secure web communications, making it a concern for any service exposing Jetty-based TLS endpoints to untrusted networks.

For European organizations, the impact of this vulnerability can be substantial, especially for those relying on Eclipse Jetty in their web infrastructure, embedded devices, or middleware solutions. A successful exploitation can lead to denial-of-service conditions, causing service outages or degraded performance. This can disrupt business operations, customer-facing services, and internal applications, potentially leading to financial losses and reputational damage. Critical sectors such as finance, healthcare, telecommunications, and government services that depend on Jetty for secure web services are particularly at risk. The vulnerability's exploitation does not compromise data confidentiality or integrity directly, but the resulting downtime could indirectly affect data availability and operational continuity. Additionally, the increased CPU usage could cause cascading failures in virtualized or cloud environments, impacting other co-hosted services. Given the remote and unauthenticated nature of the exploit, attackers can launch DoS attacks without prior access, increasing the threat surface. European organizations with stringent uptime and availability requirements must prioritize addressing this vulnerability to maintain compliance and service reliability.

1. Immediate upgrade: Organizations should upgrade Eclipse Jetty to versions beyond 9.4.38, 10.0.1, and 11.0.1 where this vulnerability is resolved. If official patches are unavailable, consider upgrading to the latest stable release that addresses TLS frame handling. 2. Network-level protections: Deploy rate limiting and deep packet inspection on network devices to detect and block malformed TLS frames or anomalous traffic patterns targeting Jetty servers. 3. TLS termination offloading: Use dedicated TLS termination proxies or load balancers that can filter and validate TLS traffic before it reaches Jetty, reducing exposure to malformed frames. 4. Resource monitoring and alerting: Implement real-time CPU and resource usage monitoring with alerting thresholds to detect unusual spikes indicative of exploitation attempts. 5. Segmentation and isolation: Isolate Jetty servers in dedicated network segments with strict access controls to limit attack vectors and lateral movement. 6. Incident response readiness: Prepare and test DoS mitigation strategies, including traffic filtering and failover mechanisms, to quickly respond to potential exploitation. 7. Vendor engagement: Engage with Eclipse Foundation or Jetty maintainers for official patches or guidance and subscribe to security advisories for timely updates.