There are several ways to exploit LogoFAIL. Remote attacks work by first exploiting an unpatched vulnerability in a browser, media player, or other app and using the administrative control gained to replace the legitimate logo image processed early in the boot process with an identical-looking one that exploits a parser flaw. The other way is to gain brief access to a vulnerable device while it’s unlocked and replace the legitimate image file with a malicious one.

In short, the adversary requires elevated access to replace a file on the EFI partition. In this case, you should consider the machine compromised with or without this flaw.

You weren’t hoping that Secure Boot saves your ass, were you?