In apache github you can get access to only the Major tag release like
"Amabri 2.4.1" release link : https://github.com/apache/ambari/releases/tag/release-2.4.1
"Ambari 2.5.1" release link : https://github.com/apache/ambari/releases/tag/release-2.5.1
Similarly other public releases can be found at: https://github.com/apache/ambari/releases
But if you are actually looking out for Patch release/Maintenance release like "Ambari 18.104.22.168.22" then you will not find it in the apache ambari github.
If you are Hortonworks customer then you can check with Hortonworks support regarding the same.
Thanks,but I need the source code of "Ambari 22.214.171.124.22" .Can I get it from Hortonworks website. I doubt that if Hortonworks provide the source code of ambari 126.96.36.199.22.