This High severity Information Disclosure vulnerability was introduced in versions 9.4.0, 9.12.0, and 9.15.0 of Jira Core Data Center. This Information Disclosure vulnerability, with a CVSS Score of 7.4, allows an unauthenticated attacker to view sensitive information via an Information Disclosure vulnerability which has high impact to confidentiality, no impact to integrity, no impact to availability, and requires user interaction. Atlassian recommends that Jira Core 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: Jira Core Data Center 9.4: Upgrade to a release greater than or equal to 9.4.21 Jira Core Data Center 9.12: Upgrade to a release greater than or equal to 9.12.8 Jira Core Data Center 9.16: Upgrade to a release greater than or equal to 9.16.0 See the release notes. You can download the latest version of Jira Core Data Center from the download center. This vulnerability was found internally.
https://jira.atlassian.com/browse/JRASERVER-77713
https://confluence.atlassian.com/pages/viewpage.action?pageId=1409286211