Jira is a proprietary issue tracking product, developed by Atlassian. It provides bug tracking, issue tracking, and project management functions. The JIRA REST APIs are used to interact with the JIRA Server applications remotely, for example, when configuring webhooks. The JIRA Server platform provides a REST API for common features, like issues and workflows.
The scanner determined that it's possible to interact with the JIRA REST APIs without providing any type of authentication.
Configure your Atlassian Jira installation to use OAuth or Basic authentication for REST APIs.