booking.com - sharing reservations
 

A heads up for anyone that plans to share a reservation made on booking.com with a 3rd party (through the "share reservation by email" link on their site).The email sent to the 3rd party is supposed to be scrubbed of all specifically identifying information (like booking number) so that a 3rd party could not change or cancel the booking. They succeeded, for the most part, but somehow left in the link that says "Change credit card details" way down the bottom of the email. That link leads right to the booking modification page, so anyone with that link can change or cancel it - no long required.

So, if you are sharing a booking with someone who should not be able to change it, consider other methods. FYI. (Booking.com notified but does not seem in a rush to fix this)