Back up the existing certificate file just to be on the safe side.
# cp /etc/pki/tls/certs/ca-bundle.crt /root/backup/

To fix the issue, just download a new certificate bundle, like the one from haxx.se.
# curl http://curl.haxx.se/ca/cacert.pem -o /etc/pki/tls/certs/ca-bundle.crt