Abstract: A corner flashing for use on a roof against a protrusion. The corner flashing comprises a base having a pair of intersecting joint edges and a wall joined in watertight relation to the base at the joint edges. The wall is an upstanding, folded, and adjustable portion. The folded portion has a plurality of folds tapering toward the base. The folded portion is inelastically deformable into a plurality of configurations between a fully open configuration and a fully closed configuration. The folded portion in the fully open configuration is approximately planar. The folded portion in the fully closed configuration has all adjacent folds contiguous. The folded portion is pivotable relative to the base by the deformation of the folded portion.