Description

The fix for CVE-2019-0199 was incomplete and did not address HTTP/2 connection window exhaustion on write in Apache Tomcat versions 9.0.0.M1 to 9.0.19 and 8.5.0 to 8.5.40 . By not sending WINDOW_UPDATE messages for the connection window (stream 0) clients were able to cause server-side threads to block eventually leading to thread exhaustion and a DoS.

Mitigation

We recommend upgrading to a version of this component that is not vulnerable to this specific issue.

Related links:

• http://web.nvd.nist.gov/view/vuln/detail?vulnId=CVE-2019-10072

• https://tomcat.apache.org/security-8.html#Fixed_in_Apache_Tomcat_8.5.41

• https://tomcat.apache.org/security-9.html#Fixed_in_Apache_Tomcat_9.0.20