This High severity DoS (Denial of Service) vulnerability known as CVE-2016-1182 was introduced in 11.2.0 of Jira Service Management Data Center and Server.

This vulnerability with a CVSS Score of 8.2 and a CVSS Vector of CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:H allows an unauthenticated attacker to take actions which have no impact to confidentiality, low impact to integrity, high impact to availability, and requires no user interaction. 

Atlassian recommends that Jira Service Management 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:

• Jira Service Management Data Center and Server 11.2: Upgrade to a release greater than or equal to 11.2.1

See the release notes. You can download the latest version of Jira Service Management Data Center and Server from the download center.

The National Vulnerability Database provides the following description for this vulnerability: ActionServlet.java in Apache Struts 1 1.x through 1.3.10 does not properly restrict the Validator configuration, which allows remote attackers to conduct cross-site scripting (XSS) attacks or cause a denial of service via crafted input, a related issue to CVE-2015-0899.