[mr_mitm]

Then why is only booking affected? Surely many of these hotels are also affiliated with hotels.com and similar portals.

[jacquesm]

Every big hospitality broker is under these kinds of attacks. Hotels.com data got exposed en-masse through one of their service providers.

[smueller1234]

Booking is the largest and thus a juicy target for both attackers and articles. Having worked there, I know that competitors had the same problems though.