What is the standard enthalpy of the reaction CO+H2O --> CO2+H2?
This is the water gas shift reaction; for which reams of thermodynamic data are available.
For leading references see here.
The standard enthalpy of reaction is +2.85 kJ.
We can use the standard enthalpies of formation of the reactants and products to calculate the standard enthalpy of reaction.
I list their values below the corresponding formulas.
Note that the substances must be in their most stable states at 298 K and 1 bar, so water is listed as a liquid.