Steps to reproduce:

Create a new Unity project
Add an empty game object to the scene
Add a script to the game object
Add the following line in Start(): AssistiveSupport.activeHierarchy = new AccessibilityHierarchy();
Build the project on Windows 10
Turn Narrator on
Run the application

Actual results: The application crashes with the following message:

Exception code: 0xc0000409 STATUS_STACK_BUFFER_OVERRUN
In module: ucrtbase.dll
Call stack:
>	ucrtbase.dll!00007ff907aa286e()
 	ucrtbase.dll!00007ff907a786dd()
 	ucrtbase.dll!00007ff907a45a0c()
 	UIAutomationCore.dll!00007ff8c9323bcb()
 	UIAutomationCore.dll!00007ff8c92ebaa1()
 	UIAutomationCore.dll!00007ff8c92eb9ea()
 	UIAutomationCore.dll!00007ff8c92eb82b()
 	UnityPlayer.dll!00007fffec0e8286()
 	0000029eea00f74a()
 	0000029eea00f68b()
 	0000029eea00f469()
 	0000029eea00ee0b()
 	0000029eea00e853()
 	0000029eea01ffd3()
 	0000029ee8e65ed8()
 	mono-2.0-bdwgc.dll!00007fffeae06e7e()
 	mono-2.0-bdwgc.dll!00007fffead48874()
 	mono-2.0-bdwgc.dll!00007fffead48960()
 	UnityPlayer.dll!00007fffebd52a69()
 	UnityPlayer.dll!00007fffebd46289()
 	UnityPlayer.dll!00007fffebd46a65()
 	UnityPlayer.dll!00007fffebd47d4f()
 	UnityPlayer.dll!00007fffeb9b39d3()
 	UnityPlayer.dll!00007fffebb81b7d()
 	UnityPlayer.dll!00007fffebb81d44()
 	UnityPlayer.dll!00007fffebb821be()
 	UnityPlayer.dll!00007fffebdd78a4()
 	UnityPlayer.dll!00007fffebdd9e2d()
 	UnityPlayer.dll!00007fffebddcc79()
 	UnityPlayer.dll!00007fffebddcefb()
 	AccessibilityTesting.exe!00007ff73c7011f2()
 	kernel32.dll!00007ff908f97374()
 	ntdll.dll!00007ff909efcc91()

Expected results: No crash appears.

Reproducible with versions: Unity 6000.3.0a5, Unity 6000.3.0b8, Windows 10

Not reproducible with versions: Windows 11

Tested on (OS): Windows 10, Windows 11

Notes:

User report on Unity Discussions