CVE-2026-108758 in Easy!Appointments
Summary
by MITRE • 10/11/2026
Easy!Appointments through 1.6.0 contains an authorization bypass vulnerability in Booking::register() that allows unauthenticated attackers to modify any appointment by supplying an appointment id without its hash. Attackers can enumerate sequential appointment ids with a self-asserted manage_mode flag to rewrite appointment details, rebind them to attacker-controlled customers, and obtain management hashes for rescheduling or cancellation.
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Analysis
by VulDB Data Team • 10/11/2026
The vulnerability identified in Easy!Appointments versions up to 1.6.0 represents a critical failure in access control mechanisms within the application's booking registration logic. Specifically, the flaw resides in the Booking::register() function, which is responsible for handling appointment creation and modification requests. The core technical issue stems from an insufficient verification of authorization tokens when processing updates to existing appointments. In secure implementations, modifying sensitive data such as appointment details typically requires a valid cryptographic hash or token that binds the request to a specific user session or administrative privilege level. However, in this vulnerable version, the system fails to strictly validate these credentials for all modification paths, allowing an unauthenticated attacker to bypass standard authentication checks entirely.
From a technical perspective, the exploitation vector relies on the predictable nature of appointment identifiers and the lack of integrity verification for associated metadata. Attackers can exploit this by supplying sequential appointment IDs in their HTTP requests while simultaneously setting a self-asserted manage_mode flag. This flag tricks the application into treating the request as if it originated from an authorized administrator or user with management privileges, despite the absence of valid authentication credentials. By omitting the required hash that normally validates the legitimacy of the modification, the attacker effectively neutralizes one layer of security control. The system accepts these malformed requests because it prioritizes the presence of the manage_mode flag over rigorous identity verification, leading to a complete bypass of authorization protocols.
The operational impact of this vulnerability is severe and multifaceted. Once an attacker successfully exploits this flaw, they gain the ability to arbitrarily modify appointment details within the application's database. This includes rewriting customer information, changing appointment times, locations, or service types, and rebinding appointments to customers controlled by the attacker. Such actions can lead to significant business disruption, including double-bookings, lost revenue from canceled services, and reputational damage due to compromised user data integrity. Furthermore, the ability to obtain management hashes for rescheduling or cancellation means that attackers can not only alter existing records but also manipulate future availability, potentially locking out legitimate users or creating fraudulent appointments under false identities.
This vulnerability aligns with CWE-287, which describes Improper Authentication, and more specifically CWE-306, the Missing Authentication for Critical Function. In terms of offensive security frameworks like MITRE ATT&CK, this behavior corresponds to techniques involving Account Manipulation and potentially Defense Evasion through privilege escalation via misconfigured access controls. The ability to enumerate sequential IDs also touches upon CWE-209, which relates to the generation of predictable values that facilitate further attacks.
To mitigate this vulnerability, immediate action is required at both the application code level and infrastructure configuration levels. Developers must enforce strict authentication checks before processing any modification requests in the Booking::register() function, ensuring that no request proceeds without valid session tokens or cryptographic hashes tied to authenticated users. Input validation should be strengthened to reject requests containing self-asserted flags unless they are accompanied by verified credentials from a trusted source. Additionally, implementing rate limiting and anomaly detection can help identify and block automated enumeration attempts targeting sequential appointment IDs. Upgrading to the latest patched version of Easy!Appointments is essential, as subsequent releases likely address these authorization flaws through improved access control lists and stricter validation routines for all administrative actions.