Appointment Booking Plugin <= 5.7.6 - Unauthenticated Authentication Bypass via Account Takeover via 'IS NOT NULL' Sentinel in 'password_reset_token' Parameter

The Appointment Booking Plugin – LatePoint | Calendar & Scheduling for WordPress plugin for WordPress is vulnerable to Authentication Bypass via Account Takeover in all versions up to, and including, 5.7.6. This is due to the `OsModel::build_conditions_query()` function in `lib/models/model.php` comparing WHERE-clause values against the literal strings `'IS NULL'` and `'IS NOT NULL'` and concatenating a match directly into SQL without binding it as a parameter, a flaw that neither `sanitize_text_field()` nor the 5.7.5 `is_scalar()` hardening guard closes, since both pass the scalar sentinel through unchanged. This makes it possible for unauthenticated attackers to send `params[password_reset_token]=IS NOT NULL` to the public `customer_cabinet__change_password` AJAX route to match every non-null `account_nonse` value, resolving to the lowest-id customer and overwriting that customer's password to an attacker-chosen value — granting full access to their bookings, orders, and PII, and, when the `wp_users_as_customers` option is enabled, takeover of the linked WordPress subscriber or customer-role account. The attacker can first identify the target customer's email by sending `params[order_intent_key]=IS NOT NULL` to the public `steps__start_from_order_intent` route, which returns the name and email from the first matching order intent, and can then self-arm the required 15-minute password-reset freshness window by triggering a reset for that customer directly.