JIRA quick edit dialog shows "XSRF security token missing" page when editing an issue with a large description

JIRA 5.0 doesn't allow editing / creating issues with really long descriptions anymore. Steps to reproduce:

• create an issue
• edit the created issue and add a really long issue description, then click Save
• JIRA shows a "XSRF security token missing" error. There is nothing in the logs indicating that an error occurred.

This works in JIRA 4.4.