Involved in the degradation of salicylate via a pathway involving coenzyme A derivative. Catalyzes the aromatic hydroxylation of salicylyl-CoA to yield gentisyl-CoA. 2-hydroxybenzoyl-CoA + H(+) + NADH + O2 = 2,5-dihydroxybenzoyl-CoA + H2O + NAD(+) By salicylate. Cells lacking this gene are unable to degrade salicylate. Belongs to the aromatic-ring hydroxylase family. KMO subfamily.