If you purchased Comodo or Sectigo SSL certificates before 30 May 2020, you may have received the AddTrust CA (certificate authority) root certificate bundle, which is normally sent along the SSL certificate, which was expired on 30 May 2020.
Using "cross-chain" technology, Sectigo has maintained new Addtrust External CA Root certificate, which has been used to create cross-certificates to Sectigo’s modern root certificates, the COMODO RSA Certification Authority and USERTrust RSA Certification Authority (as well as the ECC versions of those roots). These roots don’t expire until 2038.
Most modern clients and browsers will chain back to the modern roots that the older AddTrust was used to cross sign. Therefore, this issue will not affect most of users who are using current browsers to access the websites protected by Comodo or Sectigo SSL certificates.
What Do You Need To Do?
For SSL certificate owners and web server administrators -- no action is required. Your websites will still be accessible and trusted by most of modern browsers.
For users -- you may wish to ensure that you are using the latest version of browsers when accessing websites protected by Comodo / Sectigo SSL certificates, to ensure that you do not get any error messages when accessing the sites.
Do I need to reissue or reinstall my certificate?
No. Your certificate will remain trusted until its natural expiry date and does not need reissuance or reinstallation.
Which modern browsers and operating systems will have no issues accessing?
Apple:
macOS Sierra 10.12.1 Public Beta 2 (and later)
iOS 10 (and later)
Microsoft:
Windows XP (and later, including latest Windows 7, 8 and 10)
Windows Phone 7 (and later)
Mozilla:
Firefox 36 (and later)
Google:
Android 5.1 (and later)
Oracle:
Java JRE 8u51 (and later)
Opera:
[Browser release on December 2012 and later]
360 Browser:
SE 10.1.1550.0 and Extreme browser 11.0.2031.0 (and later)
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