What happened to your film did not originate from a camera-related leak.
It could be that the film had trouble going through the rollers in the C41 processor. That's one way that marks similar to yours can form.
Check the locking tab which locks the plate to the shutter crate. If the looseness is up/down in direction, try bending the tab down a bit. Be careful not to over do this, as too much bending may prevent the tab from locking with the crate. If your Zorki has a circular tab instead of a tongue shaped one, this solution won't work.
Before doing anything, check if the central screw which holds the internl locking tab and the external key tab is tight in its place.
If the screw is tight, but the locking tab still plays, you might be missing a spacrer or shim.