basic security check of code before publishing open source (40 php files)

We would like to publish our php software source. As always with that stuff, we want to avoid security problems with it, and especially with the code: - do we have any hardcoded passwords left in the code which should not be there? (we believe "no"...) - are there entry points for accessing features of the software without having logged in? - do you see any things that should be investigated, security issues, ...? We *know* that this task cannot be 100% completed or tested. This is the chance to take part in an interesting Open Source project - well, maybe not the most interesting one on Earth, but in a relly nice one. Our code is not really stylish. We do not use frameworks. Just PHP and some libraries. But it works quite well. The number of php files you would need to check is less than 40. Our other files like javascript, html, ... do not need a check. Most files are not too big, but one class file has about 6100 lines (shame on us!). Code is organized in classes, with some extensions. The code is on gitlab, and we also have a VM with the software installed, which can be provided. Whoever does this job should have a general interest in *reading* code. As output, we expect a list of checked tasks and file names and found problems, - where applicable with a filename and line number. We would expect some kind of "package offer", maybe listing a few items you would do for the specified amount of money. We hope for your understanding: we cannot publish the code here before it has been thoroughly checked, so we cannot send it to you before we have accepted your offer. Have a good day, and thanks for reading this!