CVE-2026-110653: Critical Authentication Bypass Vulnerability in LatePoint Appointment Booking Plugin

Executive Intelligence Brief

A critical vulnerability has been identified in the LatePoint Appointment Booking Plugin for WordPress, affecting all versions up to and including 5.7.4. This vulnerability, tracked as CVE-2026-110653, has a CVSS score of 9.1 and allows unauthenticated attackers to bypass authentication via a race condition. Successful exploitation could lead to full account compromise, including access to bookings and personal data. Immediate patching to version 5.7.5 or later is strongly recommended.

Threat Overview

The LatePoint Appointment Booking Plugin is a popular WordPress plugin used for calendar and scheduling functionalities. With a wide deployment footprint across numerous WordPress sites, this vulnerability poses a significant risk to organizations using the affected versions. Historically, race condition vulnerabilities have been challenging to identify and fix, making this a critical issue for administrators to address.

Technical Deep Dive

Vulnerability Classification

This vulnerability is classified as CWE-287, Improper Authentication. Specifically, it is an authentication bypass via a race condition in the `verifyOTP` function of the plugin. The vulnerability arises from a non-atomic read-modify-write operation on the OTP verification attempts counter.

Root Cause Analysis

The root cause of this vulnerability is the lack of atomicity in the read-modify-write operation on the OTP verification attempts counter in the `verifyOTP` function. The counter is incremented using a stale in-memory value without a conditional `WHERE attempts < 10` guard on the `UPDATE` statement or a `SELECT ... FOR UPDATE` row lock. This creates a time-of-check-to-time-of-use (TOCTOU) window that allows concurrent requests to bypass the 10-attempt lockout.

Attack Vector & Chain

The attack vector involves unauthenticated attackers who know a target customer's registered email address or phone number. These attackers can fire concurrent requests to the `auth__verify_otp` endpoint to defeat the lockout cap and brute-force the 6-digit OTP code. Successful exploitation allows attackers to authenticate as the targeted LatePoint customer, gaining full access to their account, bookings, and personal data.

Exploitation Scenario Walkthrough

Scenario: Authentication Bypass via Concurrent Requests
Reconnaissance: An attacker identifies a WordPress site using the vulnerable version of the LatePoint Appointment Booking Plugin. The attacker obtains a target customer's registered email address or phone number.
Weaponization: The attacker prepares concurrent requests to the `auth__verify_otp` endpoint, leveraging the race condition to bypass the 10-attempt lockout.
Delivery & Exploitation: The attacker sends multiple concurrent requests to the `auth__verify_otp` endpoint with the target customer's email or phone number and various OTP codes. The plugin's flawed logic allows these requests to bypass the lockout mechanism, enabling the attacker to brute-force the OTP code.
Post-Exploitation: After successfully brute-forcing the OTP code, the attacker authenticates as the targeted customer, gaining full access to their account, bookings, and personal data.
Impact Realization: The attacker can now view and modify bookings, access personal data, and potentially use this access for further malicious activities.

Exploitation in the Wild

There is no indication that this vulnerability is currently being actively exploited in the wild. However, given its critical severity and the public availability of exploit details, the likelihood of exploitation is high.

Impact Analysis

Direct Impact

Successful exploitation of this vulnerability allows attackers to bypass authentication and gain full access to a customer's account, including bookings and personal data. This could lead to unauthorized data access, modification of bookings, and potential lateral movement within the compromised WordPress site.

Downstream & Cascading Effects

The downstream effects could include unauthorized access to sensitive customer information, potential data breaches, and disruption of booking services. Additionally, if an attacker gains access to administrative accounts, they could modify plugin settings or inject malicious content into the WordPress site.

Affected Products & Versions

The vulnerability affects all versions of the LatePoint Appointment Booking Plugin up to and including 5.7.4. The fixed version is 5.7.5 or later.

Detection & Threat Hunting

Indicators of Compromise

Indicators of compromise may include:
- Unusual patterns of concurrent requests to the `auth__verify_otp` endpoint
- Multiple failed login attempts from a single IP address
- Anomalies in user account activity, such as unexpected changes to bookings or personal data

Detection Rules & Signatures

SIEM/EDR detection logic could involve monitoring for:
- Excessive requests to the `auth__verify_otp` endpoint within a short time frame
- Requests with varying OTP codes for the same user
- Successful logins from unfamiliar IP addresses
Relevant MITRE ATT&CK techniques include T1078 (Valid Accounts) and T1203 (Exploitation of Authentication Bypass).

Threat Hunting Queries

Threat hunting queries could involve searching for:
- Recent spikes in authentication attempts
- Unusual patterns of user behavior
- Anomalous network traffic to the WordPress site's authentication endpoints

Remediation & Hardening

Immediate Actions (0-24 hours)

1. Update the LatePoint Appointment Booking Plugin to version 5.7.5 or later immediately.
2. Monitor for suspicious activity related to the `auth__verify_otp` endpoint.
3. Implement additional authentication mechanisms, such as two-factor authentication, for WordPress accounts.

Short-Term Hardening (1-7 days)

1. Review and restrict access to the WordPress site's authentication endpoints.
2. Enhance monitoring of user account activity and login attempts.
3. Consider implementing a Web Application Firewall (WAF) to detect and block suspicious traffic patterns.

Strategic Recommendations

1. Regularly update all WordPress plugins and themes to the latest versions.
2. Implement a robust security monitoring system for the WordPress site.
3. Conduct regular security audits and penetration testing to identify potential vulnerabilities.

Analyst Assessment

The risk of exploitation is high due to the critical severity of the vulnerability and the public availability of exploit details. Organizations using the affected versions of the LatePoint Appointment Booking Plugin should prioritize immediate patching to prevent potential compromise. The likelihood of variants or increased exploitation is high, given the popularity of the plugin and the simplicity of the exploit.

Sources

- National Vulnerability Database (NVD): CVE-2026-110653
- Wordfence Threat Intelligence: Vulnerability Details