It depends on whether you consider attaching JTAG ICD and just reading whole state of CPU out an security attack. In some aspects just attaching an ICD to desktop CPU is simpler than attacks on physical security that involve freezing DRAM chips and reading their contents with patched BIOS or whatever. On the other hand it mostly requires attacker to have JTAG ICD that supports that particular CPU. Almost all x86 chips have some kind of ICD interface, usually very low-level and complete one. But because of low level nature of registers you see through it, JTAG register maps and so on are NDA-only and thus ICDs that support non-embedded CPUs tend to be very rare and in the realm of "you can't afford it if you have to ask the price". But they exist and buying one is more about the price than about any questions of the kind "why do you need that?". But because of rarity of these things most current research simply ignores this attack vector.
Bottom line: there is no such thing like security against local attacks on almost any kind of commodity hardware (including TPMs, excluding devices explicitly designed to be reasonably secure like gaming consoles). When you need that you also need proper tamper-proof hardware.