Clearswift MIMEsweeper For Web (a.k.a. WEBsweeper) 4.0 through 5.1 allows remote attackers to bypass filtering via a URL that does not include a .exe extension but returns an executable file.

Clearswift MIMEsweeper 5.0.5, when it has been upgraded from MAILsweeper for SMTP version 4.3 or MAILsweeper Business Suite I or II, allows remote attackers to bypass scanning by including encrypted data in a mail message, which causes the message to be marked as "Clean" instead of "Encrypted".