CVE-2025-53506: 
Java vulnerability analysis and mitigation

A critical denial-of-service vulnerability (CVE-2025-53506) was discovered in Apache Tomcat, affecting versions from 11.0.0-M1 through 11.0.8, 10.1.0-M1 through 10.1.42, and 9.0.0.M1 through 9.0.106. The vulnerability is related to uncontrolled resource consumption when an HTTP/2 client fails to acknowledge the initial settings frame that reduces the maximum permitted concurrent streams (NVD).

The vulnerability (CVE-2025-53506) allows attackers to overwhelm Apache Tomcat servers by creating excessive HTTP/2 streams within a single connection. This attack vector exploits the HTTP/2 multiplexing feature, where multiple streams can be processed simultaneously over a single TCP connection. The vulnerability has been assigned a CVSS v3.1 base score of 7.5 (HIGH) with the vector string CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H, indicating it can be exploited remotely without requiring privileges or user interaction (Cybersecurity News, NVD).

The vulnerability enables malicious actors to trigger denial-of-service conditions by rapidly creating numerous streams, which can exhaust server memory and processing resources. This can lead to significant service disruptions for web applications and services running on affected Apache Tomcat versions (Cybersecurity News).

Users are strongly recommended to upgrade to Apache Tomcat versions 11.0.9, 10.1.43, or 9.0.107, which contain the necessary fixes. The patch implements proper stream count limitations and resource management policies through commit 43477293. Network administrators should configure appropriate values for maxConcurrentStreams and monitor HTTP/2 connection patterns to detect potential abuse (NVD, Cybersecurity News).