When first published on June 6, the release notes for Firefox 60.0.2 didn’t mention anything about security, but they’ve since been updated to include a reference to a single vulnerability that is fixed in the new version.
The vulnerability fixed in Firefox 60.0.2 is flagged as having both Critical and High impact by Mozilla, and since there are as yet no details in the official vulnerability database for CVE-2018-6126, it’s difficult to know which is correct.
Regardless, if you use Firefox, you should update it as soon as possible. Depending on how it’s configured, Firefox will usually at least let you know that a new version is available within a few hours after it’s published. If not, you can usually trigger an update by clicking the ‘hamburger’ menu icon at the top right, then selecting