This High severity Third-Party Dependency vulnerability was introduced in versions 7.21.0, 7.21.1, 7.21.2, 7.21.3, 7.21.4, 7.21.5, 7.21.6, and 7.21.7 of Bitbucket Data Center and Server.

This Third-Party Dependency vulnerability, with a CVSS Score of 8.8 and a CVSS Vector of CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H allows an unauthenticated attacker to expose assets in your environment susceptible to exploitation which has a high impact to confidentiality, high 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 7.21: Upgrade to a release greater than or equal to 7.21.8

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: An attacker that is able to modify Velocity templates may execute arbitrary Java code or run arbitrary system commands with the same privileges as the account running the Servlet container. This applies to applications that allow untrusted users to upload/modify velocity templates running Apache Velocity Engine versions up to 2.2.