Possible plugin generating multiple trailing slashes

I was looking through webmaster tools and notices 377 ulrs access denied errors.

Opening the sections revealed urls being generated somewhere with up to eight trailing slashes such as

blog/tag/powder-flash////////

or

image-restore.co.uk/blog/images-from-the-old-album////////

I read it might be Yoast SEO casing this but to be honest i don’t have a clue.

It cannot be very good for my ratings has anyone come across this before?

Many thanks if anyone can point me in the right direction