What first confused me about endianness is that it is about byte order, not bit order. The latter would have seemed more logical, or is this just me?

This is a weird take. I've never put together this kind of exploit, but still I know enough to not buy this. Do people ever really craft exploits that are perfectly valid except for using the wrong endianness?

> If you’ve ever crafted a perfect shellcode and ROP chain only to have your exploit immediately crash with a SIGSEGV(a signal sent by the operating system to a program when it attempts to access a protected or invalid memory location) or EIP(a 32-bit CPU register in the x86 architecture that holds the memory address of the next machine instruction to be executed) pointing to garbage, you’ve likely met the silent killer of beginners: Endianness.

Aren't there a million other ways to get addresses wrong?

> Using x86/x86_64 gadgets and packers on a MIPS/PowerPC target (different endianness and instruction set) will not work.

"and instruction set" is carrying a lot of weight here.

This isn't like a coin flip thing: even considering architectures with configurable endianness, in 2025 it's overwhelmingly likely both host and target are little-endian. And on old, big-endian platforms, that's just one of many things you have to get right.