Logging into JIRA logs you out of Confluence (and vice-versa)

I don't know whether I should report this in JIRA or Confluence because it affects both. If I open JIRA and Confluence as tabs within the same Firefox window, clicking any link (or even refreshing) either application causes the other to logout.

To reproduce: Open both apps as tabs. Log in to both apps. Now go back to whichever app you logged into FIRST and click a link. When the page redisplays, you'll find that you're not logged in anymore. If you login again, you'll kick yourself out of the other app.