CVE-2025-53506

Apache Tomcat: DoS via excessive h2 streams at connection start

Description

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. Users are recommended to upgrade to version 11.0.9, 10.1.43 or 9.0.107, which fix the issue.

Category

7.5
CVSS
Severity: High
CVSS 3.1 •
EPSS 0.02%
Vendor Advisory apache.org
Affected: Apache Software Foundation Apache Tomcat
Published at:
Updated at:

References

Link Tags
https://lists.apache.org/thread/p09775q0rd185m6zz98krg0fp45j8kr0 vendor advisory

Frequently Asked Questions

What is the severity of CVE-2025-53506?
CVE-2025-53506 has been scored as a high severity vulnerability.
How to fix CVE-2025-53506?
To fix CVE-2025-53506, make sure you are using an up-to-date version of the affected component(s) by checking the vendor release notes. As for now, there are no other specific guidelines available.
Is CVE-2025-53506 being actively exploited in the wild?
As for now, there are no information to confirm that CVE-2025-53506 is being actively exploited. According to its EPSS score, there is a ~0% probability that this vulnerability will be exploited by malicious actors in the next 30 days.
What software or system is affected by CVE-2025-53506?
CVE-2025-53506 affects Apache Software Foundation Apache Tomcat.
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