As for those people whos PHP version didn’t update to 5.3.7,the solution said below isn’t work：
You need just to set cacert.pem to curl.cainfo.
Since PHP 5.3.7 you could do:
download https://curl.haxx.se/ca/cacert.pem and save it somewhere.
update php.ini — add curl.cainfo = “PATH_TO/cacert.pem”
I have found many ways to solve this problem,finally I found the way the similar as “paulroberts” said,but a litter more:
it is possible your /etc/pki/tls/certs/ is messed up. Back up all files in there first, and then download new certificate bundle, as described here:
curl https://curl.haxx.se/ca/cacert.pem -o /etc/pki/tls/certs/ca-bundle.crt
And once yum works again, reinstall the ca-certificates package:
yum install ca-certificates
（From LINUX CENTOS 6.3 – 14:Pycurl Error 77 – Yum repository error）
Done!!!
