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".

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 MAILsweeper for SMTP before 4.3.20 and MAILsweeper for Exchange before 4.3.20 allows remote attackers to bypass the "text analysis", possibly bypassing SPAM and other filters, by sending an e-mail specifying a non-existent or unrecognized character set.

Clearswift MAILsweeper for SMTP before 4.3.20 and MAILsweeper for Exchange before 4.3.20 allows remote attackers to cause a denial of service via (1) non-ASCII characters in a reverse DNS lookup result from a Received header, which leads to a Receiver service stop, and (2) unspecified vectors involving malformed messages, which causes "unpredictable behavior" that prevents the Security service from processing more messages.

Cross-site scripting (XSS) vulnerability in Clearswift MIMEsweeper for Web before 5.1.15 Hotfix allows remote attackers to inject arbitrary web script or HTML via the URL, which is reflected back in an error message when trying to access a blocked web site.

Clearswift MIMEsweeper for Web before 5.1.15 Hotfix allows remote attackers to cause a denial of service (crash) via an encrypted archived .RAR file, which triggers a scan error and causes the Web Policy Engine service to terminate.