Invitations to private repos can be accepted by different recipient

[CybersenshiCode]

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Hello,

I wanted to report this as a security observation to be looked at if possible.

The problem exists in the invitation mechanism of joing a private repo. The invitation is intended to a specific user with a specific email address. But, the case in hand is any one who receives this token/link can join the private repo even if he/she wasn't invited to join. Which is a possibility in MITM or phishing attacks.

This can be fixed by validating the invitation recipient email address and she/he is the one who is authorized to join a repo.

Thanks and happy to exchange opinions

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