This feature request is for both Jira Service Desk and Jira Software and happens even if Confluence and Jira share the same user base.

Steps to Replicate on Jira Service Desk

Link Jira Software or JIRA Service Desk with Confluence as per the document below:

• Providing self-help resources for your customers with a knowledge base

Detailed steps:

1. Install the latest JIRA (6.3.15) with Service Desk (2.2.1) and Confluence (5.7) versions.
2. Configure an Application Link with 2-Legged OAuth Authentication (2LOA) between the applications.
3. Create a Service Desk and link it to a Confluence Space.
4. Create a KB article on the Confluence space.
5. Log out of both applications and access the customer portal.
6. After performing a search, the relevant KB articles titles are displayed:
   
7. Clicking on the relevant article will open a pop-up asking for the user to log into Confluence to browse the KB Article.
   

Having to login into Confluence to browse the article details defeats the purpose of setting up an Application Link for authentication.

Steps to Replicate on Jira Software:

1) Create application link from Confluence to Jira Software

2) Link Confluence space to a particular project in Jira as per the guide below:
https://confluence.atlassian.com/jirasoftwarecloud/blog/2017/03/linking-confluence-spaces-to-jira-software-projects

3) In an article residing in that space - add a link to a Jira Issue

4) Log Out from Confluence

5) In JIRA, open the issue referenced in Confluence at  step 3 above, locate the link to the Confluence page and open it. Jira will prompt user to enter Confluence credentials.

Note: