When we allow our customers to redirect to cloudpage URL from Email link using cloudpagesURL() AMPScript function there is a unique qs parameter generate for each customer and if that particular customer forward the exact link from the Email which he received to someone else in that case that another user also see same (personalized) details on cloudpage of our customer to whom email was originally sent , do we have anything to tackle with this scenario or do we need to implement anything to avoid this situation ?
There is legitimately no way to get around this without setting a login/pass or similar separate authentication method. As the URL is the unique identifier, it doesn't who views it or where, it will display the same information. Any attempts to alter or adjust would be based on assumptions and guesses.
Even were you to try to do something around this, there is not really much that can be done as all the content is made prior to the email going out and there is no Client-side language available in email to adjust this based on real time context.
I agree with @Gortonington. This is precisely why forward-to-a-friend functionality is a bad idea. You don't want someone other than the recipient to update their own data or worse, opt someone else into something without their consent.
I'm a fan of explicitly creating "share" CTA buttons and/or links on your CloudPage that strip QS & PII from the URLs for sharing. More like a referral for opt-in.