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.
http://lists.opensuse.org/opensuse-security-announce/2019-06/msg00090.html
http://lists.opensuse.org/opensuse-security-announce/2019-07/msg00013.html
http://lists.opensuse.org/opensuse-security-announce/2019-07/msg00054.html
http://www.securityfocus.com/bid/107674
https://lists.apache.org/thread.html/[email protected]%3Cdev.tomcat.apache.org%3E
https://lists.apache.org/thread.html/[email protected]%3Cdev.tomcat.apache.org%3E
https://lists.apache.org/thread.html/[email protected]%3Cdev.tomcat.apache.org%3E
https://lists.apache.org/thread.html/[email protected]%3Cdev.tomcat.apache.org%3E
https://lists.apache.org/thread.html/[email protected]%3Cusers.tomcat.apache.org%3E
https://lists.apache.org/thread.html/[email protected]%3Cdev.tomcat.apache.org%3E
https://lists.apache.org/thread.html/[email protected]%3Cusers.tomcat.apache.org%3E
https://lists.apache.org/thread.html/[email protected]%3Cdev.tomcat.apache.org%3E
https://lists.apache.org/thread.html/[email protected]%3Cannounce.apache.org%3E
https://lists.apache.org/thread.html/[email protected]%3Cannounce.apache.org%3E
https://lists.apache.org/thread.html/[email protected]%3Cannounce.tomcat.apache.org%3E
https://lists.apache.org/thread.html/[email protected]%3Cannounce.tomcat.apache.org%3E
https://lists.apache.org/thread.html/[email protected]%3Cannounce.tomcat.apache.org%3E
https://lists.apache.org/thread.html/[email protected]%3Ccommits.tomee.apache.org%3E
https://lists.apache.org/thread.html/[email protected]%3Cdev.tomcat.apache.org%3E
https://lists.apache.org/thread.html/[email protected]%3Cusers.tomcat.apache.org%3E
https://security.netapp.com/advisory/ntap-20190419-0001/
https://support.f5.com/csp/article/K17321505
https://www.oracle.com/technetwork/security-advisory/cpujul2019-5072835.html
Source: MITRE
Published: 2019-04-10
Updated: 2019-05-28
Type: CWE-400
Base Score: 5
Vector: AV:N/AC:L/Au:N/C:N/I:N/A:P
Impact Score: 2.9
Exploitability Score: 10
Severity: MEDIUM
Base Score: 7.5
Vector: CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Impact Score: 3.6
Exploitability Score: 3.9
Severity: HIGH