This High severity SMTP Injection vulnerability was introduced in version 11.0.0 of Jira Service Management Data Center.

This SMTP Injection vulnerability, with a CVSS Score of 7.5 and a CVSS Vector of CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N allows an unauthenticated attacker to expose assets in your environment susceptible to exploitation which has no impact to confidentiality, high impact to integrity, no impact to availability, and requires no user interaction.

Atlassian recommends that Jira Service Management 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 Service Management Data Center 11.0: Upgrade to a release greater than or equal to 11.0.1

See the release notes (https://confluence.atlassian.com/servicemanagement/jira-service-management-release-notes-780083086.html). You can download the latest version of Jira Service Management Data Center and Server from the download center (https://www.atlassian.com/software/jira/service-management/download-archives).