A solution to the problem on local interaction of a boundary layer with an external potential flow in subsonic neighborhood of a convex profile corner vertex is found in the form of perturbations to the component values of velocity vector at the corner point. Distance from the vertex up the flow and an inverse of the Reynolds number Re calculated by critical parameter values in the flow are taken as small parameters. It is assumed that in the limit \(\text{Re}\to\infty\) the Vaglio–Laurin flow [R. Vaglio-Laurin, J. Fluid Mech. 9, 81–103 (1960; Zbl 0095.20805)] formed by a singularity generated by the profile corner is realized in the first approximation.