CVE-2025-52434 is a concurrency vulnerability classified under CWE-362, affecting the Apache Tomcat server's APR/Native connector component. The vulnerability manifests as a race condition due to improper synchronization when handling concurrent HTTP/2 connections, specifically during client-initiated connection closures. This flaw exists in Apache Tomcat versions from 9.0.0.M1 through 9.0.106 and in older 8.5.x versions (8.5.0 through 8.5.100), including some end-of-life releases. The race condition can lead to resource state inconsistencies, causing denial of service by crashing or destabilizing the server or causing it to become unresponsive. The vulnerability does not impact confidentiality or integrity but severely affects availability. It can be exploited remotely without authentication or user interaction, increasing its risk profile. Although no active exploits are reported, the CVSS score of 7.5 (high) reflects the potential impact and ease of exploitation. The issue is resolved in Apache Tomcat 9.0.107, which includes proper synchronization fixes in the APR/Native connector to handle concurrent HTTP/2 connection closures safely.

For European organizations, this vulnerability poses a significant risk to the availability of web services hosted on Apache Tomcat servers using the APR/Native connector with HTTP/2 enabled. Disruption of critical web applications, internal portals, or APIs could lead to operational downtime, affecting business continuity and service delivery. Sectors such as finance, government, healthcare, and telecommunications, which heavily rely on Apache Tomcat for scalable web infrastructure, may experience service outages or degraded performance. The lack of confidentiality or integrity impact reduces the risk of data breaches, but denial of service can indirectly affect trust and compliance with service-level agreements (SLAs). Given the remote and unauthenticated exploit vector, attackers could potentially cause widespread disruption if the vulnerability is weaponized, especially in environments with high HTTP/2 traffic.

1. Upgrade all affected Apache Tomcat instances to version 9.0.107 or later immediately to apply the official fix. 2. For environments unable to upgrade promptly, consider disabling the APR/Native connector or HTTP/2 support temporarily to mitigate exposure. 3. Implement network-level protections such as rate limiting and connection throttling to reduce the risk of exploitation via rapid connection closures. 4. Monitor server logs and network traffic for unusual patterns of HTTP/2 connection terminations or errors indicative of race condition triggers. 5. Conduct thorough testing of web applications post-upgrade to ensure stability and compatibility with the patched Tomcat version. 6. Maintain an inventory of Apache Tomcat deployments and their versions to prioritize patching efforts effectively. 7. Engage in proactive vulnerability management and incident response planning to quickly address potential exploitation attempts.