Huge astrospheres or stellar wind bubbles influence the propagation of cosmic rays at energies up to the TeV range and can act as small-scale sinks decreasing the cosmic ray flux. We model such a sink (in 2D) by a sphere of radius 10,pc embedded within a sphere of a radius of 1,kpc. The cosmic ray flux is calculated by means of backward stochastic differential equations from an observer, which is located at $r_{0}$, to the outer boundary. It turns out that such small-scale sinks can influence the cosmic ray flux at the observers location by a few permille (i.e a few 0.1%), which is in the range of the observations by IceCube, Milagro and other large area telescopes.
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