Qiling has been looking for UEFI support for a while, see their TODO file:
The EFI_DEX_Emulator is getting Qiling support!
PS: Qiling mentions how it’d be nice to fuzz UEFI with AFL:
I just noticed that the below project (which I was about to point out to the Qiling project) is no longer available, unfortunately:
CHIPSEC has a few small built-in fuzzers, some of which apply to UEFI.
The only other UEFI fuzzing project I know about is Intel’s Project Excite, an open source project which I don’t think they ever managed to open source, and I think it used KLEE instead of AFL: