Very common and almost certainly the baffle behind the rangefinder prism:
with light then coming through the sprocket drive area. (Lay the film across the gate and the streak will probably line up with the appropriate place.) Other people's experiences of sorting this one out may differ but I've found it impossible to fix in two cameras, the fit of the components under the top casting being so poor. If you shine a bright torch through the small rangefinder window in a dark room, you will see a pin point of light in the area near the sprocket drive - wind and fire the shutter a few times and retry this though, as it won't happen every time. It's more like it was a feature that was built into the later Kievs I'm afraid and that's a very late one.
On colour negative film, the streak on the final prints/scans would be orange if a leak from the back was to blame. That's a white streak, so it's a light leak on the emulsion side of the film. The fogging doesn't happen on the frame that's lined up with the film gate, it's on the previous exposure that's partially wound onto the take-up spool, if that makes sense!