Fixing link thats not secure

doc/integration/github.md

@@ -12,7 +12,7 @@ When you create an OAuth 2 app in GitHub, you'll need the following information:
 - The authorization callback URL; in this case, `https://gitlab.example.com/users/auth`. Include the port number if your GitLab instance uses a non-default port.
 
 NOTE: **Note:**
-To prevent an [OAuth2 covert redirect](http://tetraph.com/covert_redirect/) vulnerability, append `/users/auth` to the end of the GitHub authorization callback URL.
+To prevent an [OAuth2 covert redirect](https://oauth.net/advisories/2014-1-covert-redirect/) vulnerability, append `/users/auth` to the end of the GitHub authorization callback URL.
 
 See [Initial OmniAuth Configuration](omniauth.md#initial-omniauth-configuration) for initial settings.