Certificate Revocation Lists not applied correctly
Orinal source post by Cloudflare
Sep 27, 02:47 UTC
Resolved - Cloudflare has discovered that it did not correctly apply Certificate Revocation Lists to Cloudflare certificates that were used to connect to origins. This issue has been remediated.
Customers with revoked certificates configured on origins may experience elevated 526 error rates since the fix rollout was completed at 21:00 UTC September 26th.