When I looked up the problem, I saw a couple of examples of other images looking just like it. I don't recall where.
A light leak from the camera back would generally show up on the unexposed areas of the film. Something reflective inside the camera could maybe cause it. Or it's possibly a scanning artifact? I inverted your picture of the negative - it shows up a bit different in that.
Yes, unless it's just below the threshold of creating density and above the threshold to act as a pre/post-flash exposure. It looks a bit like that. But it's wise to first exclude the possibility of a digitization artefact.
When I looked up the problem, I saw a couple of examples of other images looking just like it. I don't recall where.
A light leak from the camera back would generally show up on the unexposed areas of the film. Something reflective inside the camera could maybe cause it. Or it's possibly a scanning artifact? I inverted your picture of the negative - it shows up a bit different in that.
On the neg below this one, you can see a bit of that light on the edges of the frame underneath the one youv've inverted. I'll try to find that negative.
It was Fresh film, and it's a 24mm Nikkor, possibly vingetting but I do feel there are also leaks. Back foams were shot.
So long as theres no leaks in-body or through the prism or something, it should be okay!
It's difficult to trust the edges of a scanned image because light projected through the unexposed parts can infect the edge of the image. So, it's definitely better to mask the sprocket track.
Re the reddish edges: I would be inclined to suspect the negative holder of your scanner. Reflections can cause such anomalies. Nothing much you can do about it, except crop the edges away.