CVE-2026-84766 in FluentBooking Pro Plugin
Summary
by MITRE • 09/03/2026
Unauthenticated Bypass Vulnerability in FluentBooking Pro <= 2.2.1 versions.
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Analysis
by VulDB Data Team • 09/03/2026
The vulnerability identified as an unauthenticated bypass within FluentBooking Pro, specifically affecting version 2.2.1 and earlier releases, represents a critical security flaw that undermines the fundamental authentication mechanisms of the application. This type of vulnerability allows attackers to access protected resources or execute privileged actions without providing valid credentials, effectively rendering user identity verification obsolete for specific endpoints or functionalities. In the context of web applications like FluentBooking Pro, which typically handles sensitive customer data and appointment scheduling, such a flaw is particularly dangerous as it exposes internal logic to public exploitation. The root cause often lies in improper access control checks where the application fails to verify the authentication status of incoming requests before processing them, or relies on client-side validation that can be easily bypassed using standard HTTP manipulation tools.
From a technical perspective, this vulnerability aligns with CWE-287, which describes Improper Authentication, and often overlaps with CWE-862, Missing Authorization Check. The attacker exploits the lack of server-side enforcement by sending crafted requests directly to API endpoints or administrative pages that should require login sessions. By omitting authentication tokens or cookies in these requests, the application incorrectly assumes the request is valid due to a logic error in its routing or middleware configuration. This allows the adversary to interact with features intended only for authenticated users, such as viewing other users' booking data, modifying appointment details, or accessing administrative settings. The absence of proper session validation creates an open door for automated scanning tools and manual exploitation alike, significantly lowering the barrier to entry for malicious actors.
The operational impact of this vulnerability is severe, primarily concerning confidentiality and integrity. Attackers can exfiltrate personally identifiable information (PII) including names, contact details, and payment history associated with booked appointments. Furthermore, they may alter or delete booking records, leading to significant business disruption and loss of trust among clients. In some configurations, if the unauthenticated access extends to administrative functions, it could allow for full system compromise, enabling further attacks such as cross-site scripting (XSS) injection into user-facing pages via stored data manipulation. This not only compromises individual privacy but also damages the reputation of the service provider and may lead to non-compliance with data protection regulations like GDPR or CCPA due to unauthorized access to personal data.
Mitigation strategies must focus on immediate patching and rigorous validation practices. The primary remediation is to upgrade FluentBooking Pro to a version later than 2.2.1 where this specific bypass has been addressed by the developers through corrected authentication logic. For organizations unable to update immediately, implementing Web Application Firewall (WAF) rules can help detect and block anomalous request patterns that lack valid session tokens for protected endpoints. Additionally, security teams should enforce strict server-side validation on all API calls, ensuring that every sensitive operation explicitly checks for a valid, non-expired authentication token before proceeding. Regular penetration testing focused on broken access control is also recommended to identify similar weaknesses in other parts of the application architecture. This vulnerability maps to MITRE ATT&CK technique T1078, Valid Accounts, as it allows attackers to operate with privileges they do not legitimately possess by bypassing the initial login gate.