I claim the ornamental design for a cube safety latch lock, as shown and described.
FIG. 1 is a right side anterior perspective view of a cube safety latch lock.
FIG. 2 is an anterior view of a cube safety latch lock.
FIG. 3 is a posterior view of a cube safety latch lock.
FIG. 4 is top view of a cube safety latch lock.
FIG. 5 is a bottom view of a cube safety latch lock.
FIG. 6 is a left side view of a cube safety latch lock; and,
FIG. 7 is a right side view of a cube safety latch lock.
The dash dot dash lines shown in FIGS. 1-2 and 7 that are immediately adjacent to the shaded area are the boundary of the claimed design. The dash dash broken lines shown in FIGS. 1-7 are for the purpose of illustrating an environment. None of the broken lines form any part of the claimed design.