At that point it seems like a glorified version of a bug bounty list[1].
The convenience of GSoC is that the students get to intern with pay on open source projects. If squashing bugs is the only goal, then going through their bug bounty lists and getting paid for it really is just picking a company on that list and doing it yourself. However, with a Google program behind it and the company's agreement, I'm sure the amount paid will be higher and/or more consistent.
Including my old link [2] for security/bug vulnerability discovery as well, since you get paid for these by the companies based on bug fixes or discoveries.
The value of "mentorship" or "internship" at FOSS projects are overrated, most of this projects run without clear goals and improvements are made only by "interested parties" like intel wanting their technologies to run better on Linux or the devs at GitHub optimizing "Git" for the sake of their business operations but yet not a single improvement on the UI side (obviously because it will hurt their business if suddenly people realize how easy could be using Git without GitHub).
https://developers.google.com/open-source/gci/