Dear Sir,
I do not think that this kind of log alerts have anything to do with DSpace. DSpace is using Java Technology and JSP/XML for the frontend and not at all PHP.
These requests you are seeing in Apache are probably "fishing" requests to check IF your server has a thinkphp installation and if so, IF the vulnerability exists.
The response they are getting on the other hand is that this a redirect (302), which means that they can find the content in another server, which is included in your server's response header back to the client.
To which server your Apache installation redirects the users? If it is a simple HTTP => HTTPS redirection then in the log files you will also find a lot of "NOT FOUND" (404) HTTP responses for the same requests later on in the log file if you do not have a thinkphp installation.
If not, you may want to check if you have a thinkphp installation somewhere in this, or another server and check to see if it is secured from that CVE.
Best Regards,
-Fk