CVE-2024-34750 is a vulnerability classified under CWE-755 (Improper Handling of Exceptional Conditions) and CWE-400 (Uncontrolled Resource Consumption) affecting Apache Tomcat versions 8.5.0 through 11.0.0-M20. The flaw arises during HTTP/2 stream processing when Tomcat encounters excessive HTTP headers. In such cases, Tomcat miscounts the number of active HTTP/2 streams, which leads to the application of an incorrect infinite timeout value. This causes connections that should be closed to remain open indefinitely, resulting in uncontrolled resource consumption. The vulnerability can be exploited remotely without authentication or user interaction, making it accessible to any attacker capable of sending crafted HTTP/2 requests. The primary impact is on availability, as the server may exhaust resources and become unresponsive or crash, leading to denial of service conditions. The vulnerability does not compromise confidentiality or integrity. Apache has addressed this issue in versions 11.0.0-M21, 10.1.25, and 9.0.90. Older versions, including some end-of-life releases, remain vulnerable. No known exploits are currently in the wild, but the ease of exploitation and potential impact warrant urgent attention. The vulnerability affects a widely deployed Java-based web server and servlet container used extensively in enterprise and government environments worldwide.

For European organizations, the impact of CVE-2024-34750 can be significant, especially for those relying on Apache Tomcat to host critical web applications and services. The vulnerability enables attackers to cause denial of service by exhausting server resources through persistent open connections, potentially disrupting business operations, customer-facing services, and internal applications. This can lead to financial losses, reputational damage, and operational downtime. Public sector entities and critical infrastructure providers using Tomcat are particularly at risk, as service availability is often crucial. The vulnerability's remote exploitability without authentication increases the attack surface, making it easier for threat actors to target vulnerable systems. Additionally, organizations that have not upgraded from end-of-life versions may face increased risk due to lack of vendor support and patches. The impact is compounded in environments with high HTTP/2 traffic or where resource limits are not strictly enforced, increasing the likelihood of resource exhaustion and service outages.

To mitigate CVE-2024-34750 effectively, European organizations should: 1) Immediately upgrade Apache Tomcat to the fixed versions 11.0.0-M21, 10.1.25, or 9.0.90, depending on their current deployment. 2) For environments where immediate patching is not feasible, implement network-level rate limiting and connection throttling to restrict excessive HTTP/2 header requests and limit the number of concurrent streams per client. 3) Monitor HTTP/2 traffic patterns and server resource utilization closely to detect abnormal connection behaviors indicative of exploitation attempts. 4) Configure Tomcat and underlying operating systems to enforce strict resource limits, such as maximum open connections and timeouts, to prevent resource exhaustion. 5) Review and update firewall and intrusion prevention system (IPS) rules to detect and block malformed or suspicious HTTP/2 requests. 6) Conduct regular vulnerability assessments and penetration testing focused on HTTP/2 implementations. 7) Educate DevOps and security teams about this vulnerability to ensure rapid response and patch management. These steps go beyond generic advice by emphasizing proactive traffic monitoring, resource control, and layered defense strategies.