On Saturday July 26th, an intermediate certificate issued by DigiCert that was used by online services like GitHub, BitBucket, etc expired. Since this certificate was widely cached in the keychains of many Mac OS X users, this expiration caused any connection via browser or API to raise certificate chain errors.
DigiCert has released detailed information about fixing this issue, which requires deleting the “DigiCert High Assurance EV Root CA” from the Keychain.
There haven’t been any issues reported from Linux, or Windows users, although this problem affects any client platform that locally caches intermediate certificates. DigiCert reports that it hasn’t used the expired intermediate certificate for over three years, but some computers who previously may have used it could have it cached in their local trust store.
Since this issue occurred over the weekend, it remains to be seen on Monday morning, how much effect will this OS X caching bug have on users and organization.