CVE-2026-16282: Appointment Hour Booking Auth Bypass Flaw

CVE-2026-16282 is an authentication bypass vulnerability in the Appointment Hour Booking WordPress plugin allowing price manipulation. Attackers can submit arbitrary prices, including zero or negative values. This article covers technical details, affected versions, impact, and mitigation strategies.

CVE-2026-16282 Overview

CVE-2026-16282 is a business logic vulnerability in the Appointment Hour Booking WordPress plugin before version 1.5.88. The plugin fails to validate the client-supplied booking price against the server-side configured service price. Unauthenticated attackers can submit an arbitrary final price, including zero or negative values, which the plugin stores as the authoritative booking price. This corrupts booking and payment records without requiring authentication or user interaction. The flaw maps to [CWE-287] and is exploitable remotely across the network.

Critical Impact
Unauthenticated attackers can submit arbitrary booking prices, including zero or negative amounts, corrupting booking and payment records on affected WordPress sites.

Affected Products

Appointment Hour Booking WordPress plugin versions prior to 1.5.88
WordPress sites accepting bookings through the plugin's public form
Payment workflows dependent on the plugin's stored booking price

Discovery Timeline

2026-08-08 - CVE-2026-16282 published to NVD
2026-08-11 - Last updated in NVD database

Technical Details for CVE-2026-16282

Vulnerability Analysis

The Appointment Hour Booking plugin exposes a public booking submission endpoint that accepts price data from the client. The server accepts the submitted price as authoritative rather than recalculating it from the configured service catalog. This design allows any unauthenticated visitor to manipulate the final booking price when submitting a reservation.

The vulnerability is a business logic flaw combined with missing server-side validation. Because the plugin trusts the incoming form field, negative or zero values are stored alongside the booking record. Downstream payment integrations and administrative reports rely on this corrupted value, causing financial and reporting integrity issues.

Root Cause

The root cause is the absence of server-side price reconciliation. The plugin does not compare the client-supplied price with the price defined for the selected service in the WordPress admin configuration. Trusting client-side input for authoritative financial data violates the principle of server-side validation for security-sensitive fields.

Attack Vector

An unauthenticated attacker submits a crafted HTTP POST request to the plugin's booking endpoint. The request includes a modified price parameter with an arbitrary value. The plugin records the booking with the attacker-controlled amount, and any linked payment gateway or receipt is generated against the tampered price. See the WPScan Vulnerability Analysis for further technical detail.

Detection Methods for CVE-2026-16282

Indicators of Compromise

Booking records containing zero, negative, or unusually low price values inconsistent with configured service prices.
Payment gateway transactions with amounts that do not match the service price in the plugin configuration.
Booking submissions from unauthenticated sessions with anomalous price fields in POST bodies.

Detection Strategies

Audit the WordPress database booking tables for entries where the stored price deviates from the configured service price.
Enable request logging on the WordPress site and inspect POST parameters submitted to the Appointment Hour Booking form endpoint.
Cross-reference payment processor records with plugin booking records to identify mismatches.

Monitoring Recommendations

Alert on booking submissions with price values of zero or less than a defined minimum threshold.
Monitor web application firewall (WAF) logs for repeated booking submissions from the same source with varying price fields.
Review daily booking reports for financial anomalies indicative of price tampering.

How to Mitigate CVE-2026-16282

Immediate Actions Required

Update the Appointment Hour Booking WordPress plugin to version 1.5.88 or later.
Review recent booking and payment records for entries with manipulated prices and reconcile with customers as needed.
Restrict access to the booking form using WAF rules or CAPTCHA until the patch is applied.

Patch Information

The vendor addressed the flaw in Appointment Hour Booking version 1.5.88 by enforcing server-side validation of booking prices against the configured service price. Administrators should apply the update through the WordPress plugin dashboard or by downloading the latest release from the WordPress plugin repository. Consult the WPScan Vulnerability Analysis for reference details.

Workarounds

Disable the Appointment Hour Booking plugin until the patched version is deployed.
Deploy WAF rules that reject booking submissions containing price parameters below the configured service minimum.
Manually verify each incoming booking against the configured service price before processing payment.

bash

# Configuration example: WP-CLI update command
wp plugin update appointment-hour-booking --version=1.5.88