I don't have all ca 200 UBs in my head (see https://gist.github.com/Earnestly/7c903f481ff9d29a3dd1), but I'm pretty sure all types of illegal memory accesses count as UB.

For instance from skimming the list:

- An object is referred to outside of its lifetime (6.2.4).

- The value of a pointer to an object whose lifetime has ended is used (6.2.4).

- An array subscript is out of range, even if an object is apparently accessible with the given subscript (as in the lvalue expression a[1][7] given the declaration int a[4][5]) (6.5.6).