If i recall some of this can be avoided by not allowing users to customize the dashboard, profile page, and groups page. If i remember correctly just taking that check mark off of those items on the bottom of those settings takes care of some of this. The hole had to do with allowing users access to posting js commands. Again i may be wrong on this but i think i read that someplace.
Also most cross script vunerability can be handled quite simply by using htmlspecialchars or htmlentities, trim, and strip_tags on the user side and on the server side escaping right before you post to the db and when you display user side use stripslashes on that data you escaped when you pull it from the db.
Also i forgot to mention that if the data is an integer value there is no vulnerability so if for instance they use timestamp for the month as in the first example, there is no need to validate.
Update, although i am new to PDO i do have enough experience to be able to track down items or at least see if there has been an effort to effectively sanitize. I have not found any evidence that would cause me to believe that this has not been done, they are using functions to sanitize before heading into the db and they do seem to sanitize before displaying.
That does not mean there might not be something i am not seeing, but just going thru the once over it does appear they are doing things correctly. Is there more that can be done, im sure there is because it is the same with every software, rules and coding functions are changing on a daily basis at times and it is hard to keep up with it at times.
I would recommend that the DEV people of Oxwall take a look at these items and confirm they have all been properly sanitized, i feel they are but i am not Oxwall DEV and you know much more than i do about your flow of data.