This is not a bug in wuauclt.exe per se, but a failure to handle malformed server responses.
The this pointer ( ecx ) is null. The CUpdate object was never instantiated because a previous function failed to parse an update XML node. Why Does Wuauclt.exe Crash
Note: A process can spin at high CPU for hours before eventually crashing due to a stack overflow. In this case, treat the root cause as a corruption issue. This is not a bug in wuauclt
This clears the corrupted DataStore.edb and resets the catalog store. Windows rebuilds them on the next scan. This fixes 60% of crashes immediately. Note: A process can spin at high CPU
A rogue Group Policy Object (GPO) configured a WSUS server location with a trailing slash ( http://wsus.company.com/ instead of http://wsus.company.com ). The URL parsing logic in wuauclt.exe concatenated paths: base + "/" + "client.asmx" resulting in http://wsus.company.com//client.asmx . The server responded with a 301 redirect to a non-existent SSL endpoint, and the client’s object factory did not handle the redirect failure gracefully.
Remember: wuauclt.exe is a hardworking, aging piece of code. It crashes because the data it relies upon has gone sour. Clean the data, and the process will run smoothly. If all else fails, an in-place upgrade or a fresh install of Windows will not only fix the crash but rejuvenate your entire operating system.