CVE-2025-53506 Overview
The CVE-2025-53506 vulnerability involves uncontrolled resource consumption in Apache Tomcat when an HTTP/2 client does not acknowledge the initial settings frame that reduces the maximum permitted concurrent streams. This issue impacts Apache Tomcat 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, as well as certain EOL versions.
Critical Impact
This vulnerability can lead to Denial of Service (DoS) by exhausting server resources, affecting availability.
Affected Products
- Apache Tomcat 11.0.0-M1 to 11.0.8
- Apache Tomcat 10.1.0-M1 to 10.1.42
- Apache Tomcat 9.0.0.M1 to 9.0.106
Discovery Timeline
- Not Available - Vulnerability discovered by Not Available
- Not Available - Responsible disclosure to Apache
- Not Available - CVE CVE-2025-53506 assigned
- Not Available - Apache releases security patch
- 2025-07-10 - CVE CVE-2025-53506 published to NVD
- 2025-11-04 - Last updated in NVD database
Technical Details for CVE-2025-53506
Vulnerability Analysis
The vulnerability stems from Apache Tomcat's HTTP/2 implementation where problematic client behavior can lead to server resource exhaustion. If a client does not acknowledge the HTTP/2 settings frame, the server resources may be consumed unnecessarily, leading to a potential Denial of Service (DoS) situation.
Root Cause
The root cause lies in the inadequate handling of HTTP/2 stream management where the failure to acknowledge settings leads to unchecked resource allocation.
Attack Vector
This vulnerability can be exploited remotely over the network by a malicious HTTP/2 client.
// Example exploitation code (sanitized)
# Malicious HTTP/2 request simulation
curl -X GET http://vulnerable-server.com:8080/path --http2
Detection Methods for CVE-2025-53506
Indicators of Compromise
- Unexpected spikes in server resource utilization
- Log entries showing HTTP/2 connection anomalies
- Abnormal HTTP/2 settings frame logs
Detection Strategies
Implement network monitoring tools to detect spikes in connection attempts or resource usage. Analyze HTTP/2 traffic patterns for anomalies such as unacknowledged settings frames.
Monitoring Recommendations
Deploy SentinelOne's Behavioral Detection capabilities to continuously monitor server behavior for signs of resource exhaustion and alert on unusual HTTP/2 connection patterns.
How to Mitigate CVE-2025-53506
Immediate Actions Required
- Update Apache Tomcat to the latest secure versions (11.0.9, 10.1.43, 9.0.107)
- Apply rate limiting on HTTP/2 connections
- Monitor and reset excessive connections
Patch Information
Patches for affected versions are available in Apache Tomcat versions 11.0.9, 10.1.43, and 9.0.107, which address these deficiencies.
Workarounds
Increase monitoring and set alerts for HTTP/2 traffic anomalies. Deploy SentinelOne's comprehensive endpoint protection to mitigate resource-intensive attacks.
# Configuration example
<VirtualHost *:8080>
Protocols h2 http/1.1
MaxConnectionsPerChild 1000
ErrorLog logs/http2_error_log
CustomLog logs/http2_access_log combined
</VirtualHost>
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
