MailScanner before 4.0 5-1 and before 3.2 6-1 allows remote attackers to bypass protection via attachments with a filename with (1) extra leading spaces, (2) extra trailing spaces, or (3) alternate character encodings that cannot be processed by MailScanner.
Improper Input Validation The product receives input or data, but it does
not validate or incorrectly validates that the input has the
properties that are required to process the data safely and
correctly.