CCleaner v5.33.6162 and CCleaner Cloud v1.07.3191 (32-bit builds) contained a malicious pre-entry-point loader that diverts execution from __scrt_common_main_seh into a custom loader.
Piriform CCleaner 3.26.0.1988 through 5.02.5101 writes the filenames to disk when overwriting files, which allows local users to obtain sensitive information by searching unallocated disk space.