I just checked the security logs of Zenphoto.

It is interesting to see the evolution of unsuccessful connect attemps from various IPs:
/zp-core/zp-extensions/uploader_jQuery/uploader.php (end of last year)
/zp-core/zp-extensions/zenpage/admin-pages.php (this month)

I assume there was a vulnerability in the uploader that has been fixed, and a new one in the Zenpage admin.

Attemps don't mean there are actual issues or that they have been exploited, just that someone tries to.