This High severity org.bouncycastle:bcprov-jdk18on Dependency vulnerability was introduced in versions 9.0.1, 9.1.0, 9.2.0, 9.3.0, 9.4.0, 9.5.0, 9.6.0 of Bitbucket Data Center and Server.
 
This Cryptographic Failure vulnerability, with a CVSS Score of 8.9 and a CVSS Vector of

CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:N/SC:H/SI:H/SA:N/E:U/S/AU:Y/U:Red 

allows an unauthenticated attacker to expose assets in your environment susceptible to exploitation which has high impact to confidentiality, high impact to integrity, no 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 9.4: Upgrade to a release greater than or equal to 9.4.22 

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:
 
Covert timing channel vulnerability in Legion of the Bouncy Castle Inc. BC-JAVA core on all (core modules). This
vulnerability is associated with program files FrodoEngine.Java. This issue affects BC-JAVA: from 1.71 before 1.80.2,
from 1.81 before 1.81.1, from 1.82 before 1.84.