What is kingambit weak against?

King's Gambit is considered weak against the Fischer Defense, also known as the Nimzowitsch Defense, where Black immediately plays 2...d5 instead of accepting the gambit with 2...exf4. This allows Black to counterattack in the center and quickly develop their pieces, putting pressure on White's weak pawn structure.

Additionally, the Falkbeer Countergambit is another line that can be effective against the King's Gambit. In this line, Black sacrifices a pawn to disrupt White's center and gain active piece play. This can lead to a sharp and dynamic position where Black has good chances for counterplay.

Overall, the King's Gambit is considered risky for White as it leads to open, unbalanced positions where Black has good chances to equalize or even gain an advantage. It is important for White to play accurately and quickly develop their pieces in order to compensate for the sacrificed pawn and maintain a strong position.