CA/Upcoming Distrust Actions
From MozillaWiki
Symantec
In line with a consensus proposal agreed by a number of browser vendors, Firefox is implemented a gradual distrust of all roots controlled by the CA "Symantec". The dates and associated scopes for this distrust are as follows:
- May 2018 (Firefox 60, currently due for release 2018-05-01): All certificates issued by Symantec roots before 2016-06-01.
- October 2018 (Firefox 63, currently due for release 2018-10-16): All certificates issued by Symantec roots.
You should make sure to migrate sites you control to newer or alternative certificates well before the dates given.
Certificates issued by the independently-operated Google and Apple sub-CAs are exempt, but unless you are Google or Apple you will not be using those.