mdnsNSP.dll - This module is blocked from loading into the Local Security Authority

On clean installation of MS Windows 11 Pro. 24H2 with latest iTunes 12.13.4.4 64-bit, after user logs into Windows the following message is displayed by Program Compatibility Assistant:

This module is blocked from loading into the Local Security Authority.
\Device\HarddiskVolume3\Program Files\Bonjour\mdnsNSP.dll


Obviously, the DLL belongs to Bonjour component of iTunes.


In Core Isolation settings I see that Local Security Authority protection is enabled.


On https://support.microsoft.com/en-gb/windows/core-isolation-e30ed737-17d8-42f3-a2a9-87521df09b78 I read:

Local Security Authority (LSA) protection is a Windows security feature to help prevent the theft of credentials used for signing into Windows.

The Local Security Authority (LSA) is a crucial process in Windows involved in user authentication. It’s responsible for verifying credentials during the login process and managing authentication tokens and tickets used to enable single sign-on for services. LSA protection helps prevent untrusted software from running inside LSA or from accessing LSA memory.

LSA protection is turned on by default on new installs of Windows 11 version 22H2 and 23H2 on enterprise managed devices. It’s turned on by default on all new installs of Windows 11 version 24H2 and later.


So, mdnsNSP.dll is regarded as an untrusted software regarding LSA.


I hope someone from Apple will listen to it and fix the issue.


-- rpr.

Posted on Dec 2, 2024 1:22 AM

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Posted on Mar 2, 2025 2:27 AM

Short summary on this one as problem still exists: Since Local Security Authority (LSA) protection is on per default starting with Windows 11 24H2, this prompt will appear. Bonjour might be installed through iTunes or other third-party software (like Printix that simulates AirPrint). Only fix so far, is an uninstallation (if not needed any more). If needed, there is no solution. Also, Microsoft does not offer policies to define exclusions. Turning of LSA can't be seen as acceptable solution.

In the end, Apple needs to fix their Bonjour DLL. Currently, it is not fulfilling the requirements defined by Microsoft like "digitally signed with a Microsoft signature": Configure added LSA protection | Microsoft Learn

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Jan 3, 2025 5:49 AM in response to GRBForHim

exact same thing happened to me yesterday, repair shop had to reset to factory, phone fine on 18.2 now but is no longer recognized by itunes (from MS store), works fine on my wifes laptop (with itunes from MS store), havent tried dling form apple direct, but today i get the same popup, wish there was an easy alternative to get audiobooks onto my phone from PC.

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mdnsNSP.dll - This module is blocked from loading into the Local Security Authority

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