CVE-2026-16282 in Appointment Hour Booking Plugin
Summary
by MITRE • 08/08/2026
The Appointment Hour Booking WordPress plugin before 1.5.88 does not validate a client-supplied booking price against the server-side configured service price, allowing unauthenticated users to submit an arbitrary final price (including zero or negative) that is stored as the authoritative booking price, corrupting booking and payment records.
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Analysis
by VulDB Data Team • 08/08/2026
The Appointment Hour Booking WordPress plugin vulnerability represents a critical server-side validation flaw that undermines the integrity of booking and payment processing mechanisms within the plugin's ecosystem. This weakness exists in versions prior to 1.5.88 and stems from inadequate input sanitization where client-supplied booking prices are not properly validated against server-side configured service prices. The vulnerability allows unauthenticated users to manipulate the final booking price by submitting arbitrary values including zero or negative amounts, which then become the authoritative booking price stored in the system's database.
This flaw directly impacts the plugin's core functionality and financial integrity by enabling price manipulation that can lead to significant monetary losses for service providers. When users submit maliciously crafted booking requests with manipulated prices, the system accepts these values without proper validation, creating a persistent state where incorrect pricing information becomes embedded in the booking records. The vulnerability operates at the intersection of insufficient server-side input validation and lack of proper access control mechanisms, as it does not require authentication to exploit.
From an operational perspective this vulnerability creates multiple attack vectors that can be leveraged by malicious actors to compromise financial transactions and booking accuracy. Attackers can submit bookings with zero prices to obtain free services or negative prices to potentially trigger payment reversals, while also disrupting normal business operations through corrupted booking records that may affect scheduling and revenue tracking systems. The impact extends beyond immediate financial loss as it can compromise the entire booking workflow and undermine trust in the service provider's online reservation system.
The technical implementation of this vulnerability aligns with CWE-20 Input Validation and CWE-345 Insufficient Verification of Data Authenticity, representing a classic case of inadequate server-side validation controls. This weakness enables persistent data corruption that can be exploited through simple HTTP requests without requiring complex attack chains or privileged access. The vulnerability directly maps to several ATT&CK techniques including T1213 Data From Information Repositories and T1496 Resource Hijacking, as it allows unauthorized manipulation of booking data and potential financial gain through compromised service pricing.
Mitigation strategies should prioritize immediate plugin updates to version 1.5.88 or later where the validation flaw has been addressed through proper input sanitization and server-side price verification mechanisms. Organizations should implement additional monitoring controls to detect anomalous booking price patterns and establish automated alerts for suspicious transactions. Network-level protections including web application firewalls can help detect and block malicious requests attempting to manipulate booking prices, while regular database audits should verify the integrity of existing booking records. Security teams should also consider implementing rate limiting and transaction validation checks to prevent mass exploitation attempts.