Resource exhaustion in Apache Tomcat
CVE-2025-53506
Uncontrolled Resource Consumption vulnerability in Apache Tomcat if an HTTP/2 client did not acknowledge the initial settings frame that reduces the maximum permitted concurrent streams. This issue affects Apache Tomcat: from 11.0.0-M1 through 11.0.8, from 10.1.0-M1 through 10.1.42, from 9.0.0.M1 through 9.0.106. The following versions were EOL at the time the CVE was created but are known to be affected: 8.5.0 through 8.5.100. Other EOL versions may also be affected. Users are recommended to upgrade to version 11.0.9, 10.1.43 or 9.0.107, which fix the issue.
Vulnerability class: DoS (Denial of Service)
EPSS: 0.019 (77.5th percentile) — read the EPSS interpretation.
CVSS v3 metric
CVSS v3 base score 7.5 (High). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H.
Affected products
- Apache Tomcat
- Apache Software Foundation Tomcat — versions 11.0.0-M1, 10.1.0-M1, 9.0.0.M1
Weakness classification (CWE)
Public proof-of-concept exploits
References
- security@apache.org (vendor-advisory, Mailing List, Issue Tracking, Vendor Advisory)
- af854a3a-2127-422b-91ae-364da2661108
- af854a3a-2127-422b-91ae-364da2661108
Frequently asked questions
- What is CVE-2025-53506?
- CVE-2025-53506 is a high-severity vulnerability in Apache Tomcat, classified under Uncontrolled Resource Consumption. CVSS score: 7.5/10. Published 2025-07-10.
- How severe is CVE-2025-53506?
- High severity. CVSS v3 base score is 7.5 out of 10.
- Is CVE-2025-53506 known to be exploited?
- 3 public proof-of-concept repositories are indexed. Not currently listed in the CISA KEV catalog.