The strength of halogen acids in water follows the order?

The HX bond's strength determines how strong an acid is; a weaker bond can quickly release H+.
The correct ascending order of acid strength is: $\mathrm{HF}<\mathrm{HCl}<\mathrm{HBr}$ because bond dissociation enthalpy falls from HF to HI as the size of the atom grows from F to I.