Every coin that uses KGW should apply the fix as well asap right?
Yes, I think so.
Any idea if digishield or dgw (version2) are susceptible to the same exploit?
Have not yet dig too deeply on it, but:
Digishield: not the same, but possibly similar. KGW counts a lot of blocks to calculate adjustment, digishield only one, so it quite different. In KGW, attacker can 'jump over' the block in the future, which is not possible with only 1 block. Not yet sure, but there might be another TW exploit: Can you generate 2 blocks with dT less than 2xtarget so difficulty won't rise? If you generate block with dT 0, you get diff +25%, if I calculated correctly. next question: can you generate a block with -25% difficulty with less than 2*timespan? I think you get only -12.5% with 2 blocks time, so this hole is not open :-). But not sure if there are others.
Edit: this is dogecoin digishiel, don't know others..
DGW: possibly, quick peek reveals no fix, but it might be there, have to make deeper look at it to be sure.
I must make a re-estimate on digishield. It does allow back to median 11 blocks, ie one can go back in time.
Yes, there is attack vector.