Arbitrary file overwrite via unrestricted save path

Improper authorization in pypickle 1.1.0 through 1.1.5 allows local users to overwrite arbitrary files through the save function. The save() implementation passes a caller-controlled filepath directly to open() in write-binary mode without confining it to an allowed directory or blocking traversal. Exploitation requires local low-privilege access, control of the filepath argument, and overwrite=True; reachable files can be replaced or corrupted.