Cloudflare have identified the source of the issue and are currently working to roll out a fix to the missing CORS headers.
Posted Apr 15, 2019 - 20:13 UTC
Investigating
We have been made aware of some responses lacking CORS headers from the CDN service. We are working with Cloudflare, who have recently deployed changes, to resolve this.
Posted Apr 15, 2019 - 19:54 UTC
This incident affected: CDN Service (cdnjs.cloudflare.com).