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:

• Versions of Confluence starting with 4.3.0 before 6.2.1 are affected by this vulnerability.

Fix:

• Confluence Server 6.2.1 is available to download from [https://www.atlassian.com/software/confluence/download].

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]:

Navigate to !https://confluence.atlassian.com/download/attachments/590259974/Cog.png! > General Configuration

Choose In-app Notifications in the left-hand panel

Select does not provide in-app notifications.

The workbox icon !https://confluence.atlassian.com/conf61/files/877187111/877187147/1/1489126934141/WorkboxIcon.png! will disappear from the Confluence top menu bar.

Acknowledgements
Atlassian would like to credit Mathias Frank of SEC Consult Vulnerability Lab for reporting this issue to us.