Access Violation in W3proxy.exe Because of HTTP VARY Header Processing (295090)
The information in this article applies to:
- Microsoft Internet Security and Acceleration Server 2000
This article was previously published under Q295090 SYMPTOMS
When an outgoing HTTP request is made through Internet
Security and Acceleration (ISA) Server, an access violation may occur in W3proxy.exe, causing the Web Proxy service to terminate.
CAUSE
The access violation may occur if the Web browser client's HTTP request contains more than eight HTTP headers in a specific order and the Web server's HTTP response contains a VARY header for some of the HTTP request headers.
Typically, this access violation occurs only if there is a downstream (intermediate) proxy server that is adding HTTP request headers to the Web browser client's request between the Web browser client and ISA Server.
RESOLUTIONA supported fix is now available from Microsoft, but it is only intended to correct the problem that is described in this article. Apply it only to computers that are experiencing this specific problem. This fix may receive additional testing. Therefore, if you are not severely affected by this problem, Microsoft recommends that you wait for the next ISA Server 2000 service pack that contains this hotfix. To resolve this problem immediately, contact Microsoft Product Support Services to obtain the fix. For a complete list of Microsoft Product Support Services phone numbers and information about support costs, visit the following Microsoft Web site: NOTE: In special cases, charges that are ordinarily incurred for support calls may be canceled if a Microsoft Support Professional determines that a specific update will resolve your problem. The typical support costs will apply to additional support questions and issues that do not qualify for the specific update in question.
The English version of this fix should have the following file attributes or later:
Date Time Version Size File name
----------------------------------------------------
5/6/2001 02:03PM 3.0.1200.64 373,520 W3proxy.exe
STATUSMicrosoft has confirmed that this is a problem in the Microsoft products that are listed at the beginning of this article. MORE INFORMATION
The HTTP VARY response header is used by a Web server to signal that it has multiple possible responses and, using server-driven negotiation, is returning its best guess as to the proper response. The VARY response header contains field names that are request headers that may be used to select that specific response. The VARY header may have Accept-Language, Accept-Encoding, Accept-Charset, User-Agent, or other fields that define how the page was selected.
| Modification Type: | Major | Last Reviewed: | 4/7/2006 |
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| Keywords: | kbQFE KBHotfixServer kbenv kbprb KB295090 |
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