On the 01.12.2017 security researcher reported a XSS vulnerability affecting the booking.com website via the Open Bug Bounty coordinated vulnerability disclosure program.
Vulnerability submitted via Open Bug Bounty| 1 December, 2017 16:09 GMT
Generic security notifications sent to website owner| 1 December, 2017 16:12 GMT
Notification sent to subscribers (without technical details)| 1 December, 2017 18:17 GMT
If you are the website owner or administrator please contact the researcher directly to get vulnerability details and proceed to coordinated disclosure.