This is amazing, Windows Defender used the open source unrar code, but changed all the signed ints to unsigned for some reason, breaking the code. @halvarflake noticed and got it fixed. Remote SYSTEM memory corruption https://t.co/gsx9ZMk1Hz
Apparently, Microsoft forked that version of unrar and incorporated the component into its operating system's antivirus engine. That forked code was then modified so that all signed integer variables were converted to unsigned variables, causing knock-on problems with mathematical comparisons. This in turn left the software vulnerable to memory corruption errors, which can crash the antivirus package or allow malicious code to potentially execute.