Apache Tomcat Coyote vulnerable to Denial of Service via excessive HTTP/2 streams
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. Users are recommended to upgrade to version 11.0.9, 10.1.43 or 9.0.107, which fix the issue.
02 / AFFECTED SOFTWARE
Affected packages
273 explicit affected versions
273 explicit affected versions
03 / CONNECTIONS
Connected vulnerabilities
04 / EVIDENCE
Source records
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 through 11.0.8, from 10.1.0 through 10.1.42, from 9.0.0 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.
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. Users are recommended to upgrade to version 11.0.9, 10.1.43 or 9.0.107, which fix the issue.
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.
05 / REFERENCES
Further evidence
- http://www.openwall.com/lists/oss-security/2025/07/10/13
- https://lists.apache.org/thread/p09775q0rd185m6zz98krg0fp45j8kr0
- https://lists.debian.org/debian-lts-announce/2025/07/msg00009.html
- https://nvd.nist.gov/vuln/detail/CVE-2025-53506
- https://github.com/apache/tomcat
- https://github.com/apache/tomcat/commit/2aa6261276ebe50b99276953591e3a2be7898bdb
- https://github.com/apache/tomcat/commit/434772930f362145516dd60681134e7f0cf8115b
- https://github.com/apache/tomcat/commit/be8f330f83ceddaf3baeed57522e571572b6b99b
- https://github.com/CVEProject/cvelistV5/tree/main/cves/2025/53xxx/CVE-2025-53506.json