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How the CVE Works
CVE-2025-53506 is an HTTP/2 vulnerability in Apache Tomcat where a malicious client can exploit unacknowledged settings frames to cause uncontrolled resource consumption. If the client ignores the server’s initial settings frame (reducing max concurrent streams), Tomcat fails to enforce the limit, leading to excessive memory and thread usage. This affects versions 11.0.0-M1 to 11.0.8, 10.1.0-M1 to 10.1.42, and 9.0.0.M1 to 9.0.106. Attackers can trigger denial-of-service (DoS) by flooding the server with unprocessed streams, exhausting system resources.
DailyCVE Form
Platform: Apache Tomcat
Version: 9.0.0.M1-9.0.106
Vulnerability: Resource exhaustion
Severity: Critical
Date: 07/29/2025
Prediction: Patch by 08/15/2025
What Undercode Say
Check Tomcat version ./catalina.sh version Mitigation (pre-patch) server.max-concurrent-streams=100 Exploit PoC (simulated) h2load -n 10000 --max-concurrent-streams=0 http://target:8080
How Exploit
Malicious clients send endless HTTP/2 streams, bypassing server limits, causing DoS via resource starvation.
Protection from this CVE
Upgrade to Tomcat 11.0.9/10.1.43/9.0.107.
Impact
System instability, service disruption, memory exhaustion.
Sources:
Reported By: nvd.nist.gov
Extra Source Hub:
Undercode
