I found this table on the curb a while back, less the leg hardware. No a relative could use it, and I'm wondering how to fix it up.
Cut a couple 2x4 sections to fill the truncated-triangular area and screw through them into all surfaces?
The legs have a hollow center drilled out, at the top, so I assume some metal piece with threaded holes fit there, and a metal plate anchored that to the skirt (?).
Another view:
I realize this is already answered, but if you are looking to fix this fast and don't want to buy something like @jordanlund said to do (the better answer), you can cut a peice with two 45's in opposition, which will wedge into the corner, then put two holes, lined up with the table leg, to attach the through bolt to. Just make sure to use a hole saw or paddle bit to hog out the surface so you can get a larger washer in there for the bolt to act on.