Confluence did not check if a user had permission to view a page when creating a workbox notification about new comments. An attacker who can login to Confluence could receive workbox notifications, which contain the content of comments, for comments added to a page after they started watching it even if they do not have permission to view the page itself.
Affected versions:
Fix:
Workaround
If you are unable to upgrade to the fixed version or newer and need a workaround, you will need to disable in-app notifications from workbox as per the instructions [found here|https://confluence.atlassian.com/doc/configuring-workbox-notifications-301663830.html]:
Acknowledgements
Atlassian would like to credit Mathias Frank of SEC Consult Vulnerability Lab for reporting this issue to us.