DoS (Denial of Service) org.apache.tomcat.embed:tomcat-embed-core Dependency in Bitbucket Data Center and Server

This High severity org.apache.tomcat.embed:tomcat-embed-core Dependency vulnerability was introduced in versions 8.9.0 and 8.19.0 of Bitbucket Data Center and Server.

This org.apache.tomcat.embed:tomcat-embed-core Dependency vulnerability, with a CVSS Score of 7.5 and a CVSS Vector of CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H allows an unauthenticated attacker to expose assets in your environment susceptible to exploitation which has no impact to confidentiality, no impact to integrity, high impact to availability, and requires no user interaction. 

Atlassian recommends that Bitbucket Data Center and Server customers upgrade to latest version, if you are unable to do so, upgrade your instance to one of the specified supported fixed versions:
	
	* Bitbucket Data Center and Server 8.9: Upgrade to a release greater than or equal to 8.9.18
	
	* Bitbucket Data Center and Server 8.19: Upgrade to a release greater than or equal to 8.19.7
	
	

h2. Data Center 

||Affected versions||Fixed Versions||
|from 8.19.0 to 8.19.6|8.19.7|
|from 8.9.0 to 8.9.17|8.19.7 or 8.9.18|
|Any earlier versions|8.19.7 or 8.9.18|

h2. Server 

||Affected versions||Fixed Versions||
|from 8.9.0 to 8.9.17|8.9.18|
|Any earlier versions|8.9.18|

See the release notes (https://confluence.atlassian.com/bitbucketserver/release-notes). You can download the latest version of Bitbucket Data Center and Server from the download center (https://www.atlassian.com/software/bitbucket/download-archives).

The National Vulnerability Database provides the following description for this vulnerability: Improper Handling of Exceptional Conditions, Uncontrolled Resource Consumption vulnerability in Apache Tomcat. When processing an HTTP/2 stream, Tomcat did not handle some cases of excessive HTTP headers correctly. This led to a miscounting of active HTTP/2 streams which in turn led to the use of an incorrect infinite timeout which allowed connections to remain open which should have been closed.

This issue affects Apache Tomcat: from 11.0.0-M1 through 11.0.0-M20, from 10.1.0-M1 through 10.1.24, from 9.0.0-M1 through 9.0.89.

Users are recommended to upgrade to version 11.0.0-M21, 10.1.25 or 9.0.90, which fixes the issue.