Public Vulnerability Reports

Blue Coat Systems WinProxy Host Header Stack Overflow Vulnerability



BlueCoat WinProxy is an Internet sharing proxy server designed for small
to medium businesses. In addition to Internet sharing Winproxy also
hosts a series of security, anti-spam and anti-spyware capabilities.

More information can be located from the vendors site at:


Remote exploitation of a buffer overflow vulnerability in Blue Coat
Systems Inc.'s WinProxy allows for the remote execution of arbitrary
code by attackers.
The vulnerability can be triggered by sending an overly long Host:
string to the web proxy service.


Exploitation of this vulnerability is trivial. An overly long header
directly overwrites the SEH handler for the frame allowing for control
over EIP.


iDefense has confirmed this vulnerability in WinProxy 6.0. All previous
versions are suspected to be vulnerable.


Disabling the WinProxy web proxy protocol will prevent this attack.


Blue Coat has released WinProxy 6.1a to address this vulnerability.


The Common Vulnerabilities and Exposures (CVE) project has assigned the
name CAN-2005-4085 to this issue. This is a candidate for inclusion in
the CVE list (, which standardizes names for
security problems.


12/07/2005   Initial vendor notification
12/08/2005   Initial vendor response
01/05/2006   Coordinated public disclosure


This vulnerability was discovered by FistFuXXer.

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Copyright © 2006 Verisign, Inc.

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