[aidenn0]

IMO All it exposed was writing past the end of buffers.

There was no memory corruption previously due to partially to luck, and partially to heavy testing (which would have exposed most forms of memory corruption).

I think it is fare to say that the change was a cause of the vtable corruption occurring, since without the change it didn't happen.

Once this is discovered, you need to rethink your change plan for the next release; if you back out this one change, your software will return to a working state. Whether doing that, or fixing your buffer overflow is the correct thing to do depends on a lot of specific factors.