Is there a bug in ASP.NET's User-Agent interpretation for custom builds of Firefox?

For the user agent string

Mozilla/5.0 (Windows; U; Windows NT 5.1; en-GB; rv:1.9.2) Gecko/20100115 Firefox/3.6 (.NET CLR 3.5.30729)

HttpContext.Current.Request.Browser.MajorVersion returns 3 and HttpContext.Current.Request.Browser.MinorVersion returns 5. So far so good.

However for this user agent string (seen in the wild by one of my users)

Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.9.2) Gecko/20100115 (CK-Finbu.com) Firefox/3.6 (.NET CLR 3.5.30729)

HttpContext.Current.Request.Browser.MajorVersion returns 1 and HttpContext.Current.Request.Browser.MinorVersion returns 9. It 开发者_如何学JAVAlooks like ASP.NET has picked up the numbers from the CVS tag info rather than the browser version.

Does this mean that ASP.NET's user agent parsing is broken?

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Seems you'll need to tweak your mozilla.browser file (in %windir%\Microsoft.NET\Framework\v2.0.50727\CONFIG\Browsers\ folder).

Around line 188, you'll see this (regex to match Firefox browser):

"Gecko\/\d+ Firefox\/(?'version'(?'major'\d+)(?'minor'\.[.\d]*))"

Should be

"Gecko\/\d+(?: \S+)? Firefox\/(?'version'(?'major'\d+)(?'minor'\.[.\d]*))"