This High severity DoS (Denial of Service) vulnerability was introduced in versions 9.4.0 and 10.2.0 of Bitbucket Data Center.

This DoS (Denial of Service) vulnerability, with a CVSS Score of 7.3 and a CVSS Vector of CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:L allows an unauthenticated attacker to expose assets in your environment susceptible to exploitation, which has low impact to confidentiality, low impact to integrity, low impact to availability, and requires no user interaction.

Atlassian recommends that Bitbucket Data Center 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 10.2: Upgrade to a release greater than or equal to 10.2.7
• Bitbucket Data Center 9.4: Upgrade to a release greater than or equal to 9.4.26

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:

Always-Incorrect Control Flow Implementation vulnerability in Apache Tomcat's rewrite valve meant that if the first condition in an OR chain matched, subsequent non-OR conditions were skipped.

This issue affects Apache Tomcat: from 11.0.0-M1 through 11.0.22, from 10.1.0-M1 through 10.1.55, from 9.0.0.M1 through 9.0.118, from 8.5.0 through 8.5.100. Other versions that have reached end of support may also be affected.

Users are recommended to upgrade to version 11.0.23, 10.1.56 or 9.0.119, which fix the issue.