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.
describes (1)
Related CVEs.
| ID | severity | exploitable | ||
|---|---|---|---|---|
| CVE-2025-53506US | — | — | ||
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 st… | ||||
references
External citations — patches, advisories, analysis.
- http://www.openwall.com/lists/oss-security/2025/07/10/13WEB
- https://github.com/apache/tomcatPACKAGE
- https://github.com/apache/tomcat/commit/2aa6261276ebe50b99276953591e3a2be7898bdbWEB
- https://github.com/apache/tomcat/commit/434772930f362145516dd60681134e7f0cf8115bWEB
- https://github.com/apache/tomcat/commit/be8f330f83ceddaf3baeed57522e571572b6b99bWEB
- https://lists.apache.org/thread/p09775q0rd185m6zz98krg0fp45j8kr0WEB
- https://lists.debian.org/debian-lts-announce/2025/07/msg00009.htmlWEB
- https://nvd.nist.gov/vuln/detail/CVE-2025-53506ADVISORY
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