I have a hosting at OVH. Recently I enabled their new CDN Security service and everything worked fine until I started receiving 403 error messages. I found the culprit, turned out this error message was triggered every time a user tried to send something via forms that had './' in paths. I successfully managed to remove them all from my website, however, making them disappear from my forum turned out to be not so easy as still a lot of them remain and they tend to cause issues which results in my users seeing a lot of 403s. Is there any way to get rid of these './' and replace them with something like 'mywebsite.com/forum/'?
You should try to fix the actual problem and not work around it. Removing a perfectly valid ./ is a workaround for the problem you created. If you can't change the settings of their CDN security thing, you should just disable it as it is broken.