Summary

It is clearly stated in the Working with Epics documentation:

"The functions for managing epics require different permissions. For example, you need the 'Edit Issues' permission to add an issue to an epic." 

That being said, an epic still shows as an option(in the Epic Link dropbox) for a non-Admin user who has no permission to edit the epic.

Users become confused about what they have actually achieved when they see an epic that looks like a viable option in the dropbox, and when they receive a message claiming that their changes were accepted.  After completing the steps below, the story is not linked to the epic.

Environment

Tested against 7.3.4 and 6.4.14(customer's version)

Steps to Reproduce

1. Create an epic in a project and set the permission scheme to only allow Administrators to 'Edit Issues'
2. Create a story in a different project where non-admin user has 'Edit Issues' permission
3. Add the story to the epic by clicking the Edit button and selecting the epic from Step 1 in the Epic Link dropbox

Expected Results

The epic should not show up as an option in the Epic Link dropbox, and/or the user should not receive an '<ISSUE-KEY> has been updated' pop-up. 

Actual Results

Pop-up appears and states '<ISSUE-KEY> has been updated', however the link to the epic does not occur.

Workaround

Have an Admin user add the story to the epic.  Granting the non-Admin users Edit Issues permission in the project containing the epic is not an option.