Microsoft KB Archive/199806

= IIS: Headers Containing White Spaces May Return a 404 Error =

Article ID: 199806

Article Last Modified on 6/22/2005

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APPLIES TO


 * Microsoft Internet Information Server 4.0

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This article was previously published under Q199806



We strongly recommend that all users upgrade to Microsoft Internet Information Services (IIS) version 6.0 running on Microsoft Windows Server 2003. IIS 6.0 significantly increases Web infrastructure security. For more information about IIS security-related topics, visit the following Microsoft Web site:

http://www.microsoft.com/technet/security/prodtech/IIS.mspx



SYMPTOMS
If a request to an Internet Information Server (IIS) Web server contains a "HOST:" entry that contains a space between the HOST and the colon (HOST :), the Web server will return a 404 error message (not found). This information is found in the headers of the request sent by the browser to the Web server. This problem does not occur with a standard browser (Netscape or Internet Explorer).



CAUSE
All "headername:" information presented to Internet Information Server (including 'host:') is assumed to not contain a space. There is no HTTP error code for "Server Not Found," therefore the server returns a 404 error message.

Keywords: kbprb kbpending KB199806

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