The CPU certainly does have at least patchable control store. Even ignoring that, there are certainly at least two significant binary blobs still remaining: EC

The CPU certainly does have at least patchable control store. Even ignoring that, there are certainly at least two significant binary blobs still remaining: EC firmware and microcode for e1000. First probably has no major security implications, second is slightly weird as there were security-significant erratas in e1000 that were fixed by microcode update, but on the other hand it's probably more of "random undocumented configuration options" than "executable code" (for some reason Intel tends to call any random binary blob "microcode").