Excessive SETTINGS Frames and Thread Exhaustion DoS Vulnerability in Apache Tomcat

CVE-2019-0199 · MEDIUM Severity

AV:N/AC:L/AU:N/C:N/I:N/A:P

The HTTP/2 implementation in Apache Tomcat 9.0.0.M1 to 9.0.14 and 8.5.0 to 8.5.37 accepted streams with excessive numbers of SETTINGS frames and also permitted clients to keep streams open without reading/writing request/response data. By keeping streams open for requests that utilised the Servlet API's blocking I/O, clients were able to cause server-side threads to block eventually leading to thread exhaustion and a DoS.

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