After extracting the POC and installing build-essential, I still get this:
nasm -O0 -felf64 -o zenleak.o zenleak.asm
make: nasm: No such file or directory
make: ** [Makefile:11: zenleak.o] Error 127
When you evaluate Keepassium could you look into if the application honors not contacting anything on the internet? For me this is a major point of feeling secure when using the application and iOS has no way to block apps from accessing the internet.