Windows Server 2008 R2 SP1装KB4533012后ASP.NET会话丢失求助

Yep, you’ve encountered a well-documented compatibility issue between legacy ASP.NET applications, Flex Grid, and the SameSite cookie enforcement added by the KB4533012 security patch. Let’s break down why this happens and how to fix it:

Why This Is Happening #

KB4533012 adds support for the SameSite cookie attribute to Windows Server 2008 R2 SP1, aligning it with modern browser security standards. Here’s where the conflict arises:

• Older ASP.NET versions (typically targeting .NET Framework 4.5 or earlier, common on Server 2008 R2) don’t natively handle the SameSite attribute. Before the patch, your session cookies were sent without this attribute, and browsers treated them as SameSite=Lax (or even None in older browser versions).
• Flex Grid’s SWF component makes requests that often fall outside the Lax policy—for example, cross-origin POST requests or requests initiated from embedded SWFs. When KB4533012 is applied, the system starts adding implicit SameSite=Lax to cookies that don’t specify the attribute. Browsers then block these cookies for the SWF’s requests, causing your session to drop and forcing logouts.
• Additionally, older Flex SWF implementations may not properly parse or forward cookies with the SameSite attribute, exacerbating the issue.

Fixes to Try #

1. Temporary Workaround (Not Recommended Long-Term) #

Uninstall KB4533012 to revert the SameSite cookie enforcement. This will restore your Flex Grid functionality, but you’ll lose the security updates included in the patch—so only use this as a short-term stopgap while implementing a permanent fix.

2. Permanent Solutions #

Option A: Upgrade .NET Framework and Configure SameSite

If possible, upgrade your ASP.NET application to target .NET Framework 4.7.2 or later. These versions natively support the SameSite attribute, letting you explicitly configure your session cookies to work with Flex Grid:

• Add these settings to your web.config to set the session cookie’s SameSite property to None (required for cross-origin/SWF requests) and ensure it’s marked Secure (a browser requirement for SameSite=None):

  <system.web>
    <sessionState cookieSameSite="None" />
    <httpCookies requireSSL="true" />
  </system.web>
  

  Note: Your site must be running over HTTPS for SameSite=None to work—browsers ignore this attribute for HTTP connections.

Option B: Manually Modify Cookies with an HttpModule (If You Can’t Upgrade .NET)

If upgrading the .NET Framework isn’t feasible, create a custom HttpModule to inject the SameSite=None; Secure attribute into your session cookies. Here’s a simplified example:

public class SameSiteCookieModule : IHttpModule
{
    public void Init(HttpApplication context)
    {
        context.PostReleaseRequestState += OnPostReleaseRequestState;
    }

    void OnPostReleaseRequestState(object sender, EventArgs e)
    {
        var app = (HttpApplication)sender;
        if (app.Response.Cookies["ASP.NET_SessionId"] != null)
        {
            var cookie = app.Response.Cookies["ASP.NET_SessionId"];
            cookie.Path += "; SameSite=None; Secure";
        }
    }

    public void Dispose() { }
}

Register the module in your web.config:

<system.webServer>
  <modules>
    <add name="SameSiteCookieModule" type="YourNamespace.SameSiteCookieModule" />
  </modules>
</system.webServer>

Option C: Adjust Flex Grid Request Behavior

Check if your Flex Grid SWF can be configured to send requests in a way that complies with SameSite=Lax rules—for example, using GET requests instead of POST where possible, or ensuring the SWF is hosted on the same domain as your ASP.NET application. This is more limited, but might help if other fixes aren’t viable.

Summary #

This issue stems from a mismatch between legacy ASP.NET/Flex Grid cookie handling and modern SameSite security standards enforced by KB4533012. The most robust fix is upgrading your .NET Framework and explicitly configuring SameSite cookies, but the HttpModule approach works if upgrades aren’t possible.

内容的提问来源于stack exchange，提问作者yuc