SharePoint security fixes released with November 2025 PU and offered through Microsoft Update

9 Comments

1. 

   Simon
   On 18. November 2025 Permalink

   We have SharePoint SE server – single server Farm (October 2025 CU). Everything seems to work OK.
   I have a problem with SharePoint November CU update. Install and configuration is working without errors, but server is broken afterwards.
   I have a problem with removing Local service account from SharePoint server, because SharePoint Administration service is running as Local service account. I changed all other SharePoint services to run as domain accounts (as written in
   https://blog.stefan-gossner.com/2025/09/11/trending-issue-sharepoint-fixes-fail-to-install-after-installation-of-september-2025-cu/)
   I really don’t know what should I do…..
   Any help would be appreciated.
   Thanks.

   Reply
   1. 

      Stefan Goßner
      On 18. November 2025 Permalink

      Hi Simon,
      if the installation completed without an error, you are fine and don’t have to bother about the local system account.
      What do you mean with “broken”?
      Cheers,
      Stefan

      Reply
   2. 

      Mattias
      On 20. November 2025 Permalink

      Hi Simon!

      One of the single server SharePoint SE farms I am managing “broke” after patching with October CU last month. And by broke I mean that when accessing CA or root-site on web application I got 500 internal server error. For me, both the installation of binaries and PS-config went thru without any error at all. After extensive troubleshooting that ended up with a ticket to MS we found out that the SPRequestFilterModule in IIS was empty.

      The description of the issue and the solution is described in this article by Stefan:
      https://blog.stefan-gossner.com/2023/10/17/trending-issue-module-sprequestfiltermodule-could-not-be-found-after-september-october-2023-cu/

      I hope you have the same issue that I had, and that this helps.

      Regards
      Mattias

      Reply
      1. 

         carl
         On 25. November 2025 Permalink

         Same happened on one of mine (july CU to nov CU jump) – seems strange for an issue almost 2 years old.

         Reply
         1. 

            Stefan Goßner
            On 25. November 2025 Permalink

            Hi Carl,
            no this is not strange. It happens if you disabled AMSI in the past. Since September CU AMSI is always enabled and cannot be disabled.
            So AMSI configuration problems will now suddenly show up if they were not resolved before.
            Cheers,
            Stefan

            Reply
            1. 

               Mattias
               On 25. November 2025 Permalink

               Hi!

               Just to add to your comment Stefan, AMSI was configured and enabled on full mode for the environment I had the issue.

               Regards
               Mattias

   3. 

      Simon
      On 11. December 2025 Permalink

      I installed December updated and everything works OK!!!
      So, I think that the problem was in November update.

      Regards,

      Simon

      Reply
2. 

   Lukasz Walkowicz
   On 9. December 2025 Permalink

   We observe intermittent bursts of “A process serving application pool ‘APP POOL NAME’ suffered a fatal communication error with the Windows Process Activation Service” System Error 5011 on our minrole WFE with DC servers. This sometimes exceeds 10 times within 5 minutes interval and therefore triggers the Rapid-Fail on the app pool, causing 503 for the users. Since the timings are totally random (day or night) and process IDs are different each time it is rather hard to pinpoint exact cause for this.

   Reply
   1. 

      Stefan Goßner
      On 9. December 2025 Permalink

      Hi Lukasz,
      there is a large number of possibilities which can cause this.
      I would suggest to open a support case with Microsoft to get this analyzed.
      Cheers,
      Stefan

      Reply