CVE-2026-11901

The WP Hotel Booking plugin for WordPress is vulnerable to Insufficient Verification of Data Authenticity in all versions up to, and including, 2.3.1. This is due to the `web_hook_process_paypal_standard()` IPN handler selecting its PayPal validation endpoint from the attacker-controlled `$_REQUEST['test_ipn']` parameter, force-upgrading any `pending` transaction to `completed` when `test_ipn=1`, and omitting post-verification checks on `receiver_email`, `mc_currency`, and `txn_id` uniqueness after receiving a `VERIFIED` response from PayPal. This makes it possible for unauthenticated attackers to mark arbitrary hotel bookings as fully paid without submitting genuine payment to the merchant — either by routing IPN validation through PayPal's sandbox using a free sandbox account, or by replaying a previously verified IPN from a nominal payment to an attacker-controlled PayPal account. An attacker requires only a free PayPal sandbox account (or any PayPal account) to obtain a `VERIFIED` response; no site credentials or special configuration are needed.

We have discovered 1,804 live websites that are affected by CVE-2026-11901.

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Affected Software

Product	Wp Hotel Booking
Category	Wordpress Plugins
Vulnerable Domains	1,804 live websites (99% of Wp Hotel Booking install base)
Vulnerable Versions	from 0 through 2.3.1
Vulnerable Versions Count	47 versions ( 98% of all versions)