CVE-2026-23622: Easy!Appointments CSRF Vulnerability

CVE-2026-23622 Overview

CVE-2026-23622 is a Cross-Site Request Forgery (CSRF) vulnerability in Easy!Appointments, a popular self-hosted appointment scheduling application. The vulnerability exists in versions 1.5.2 and earlier, where the CSRF protection mechanism in application/core/EA_Security.php only validates CSRF tokens for POST requests, allowing attackers to bypass security controls using GET requests. Since several critical application endpoints accept parameters via GET or $_REQUEST while performing state-changing operations, an attacker can craft malicious links or embed requests to perform unauthorized actions on behalf of authenticated administrators.

Critical Impact

Successful exploitation allows attackers to create rogue admin accounts, modify existing admin credentials, and achieve full administrative account takeover, potentially compromising the entire appointment scheduling system and sensitive customer data.

Affected Products

• Easy!Appointments version 1.5.2 and earlier
• Self-hosted Easy!Appointments installations with default CSRF configuration

Discovery Timeline

• 2026-01-15 - CVE CVE-2026-23622 published to NVD
• 2026-01-16 - Last updated in NVD database

Technical Details for CVE-2026-23622

Vulnerability Analysis

The vulnerability stems from an incomplete CSRF protection implementation in the Easy!Appointments security module. The csrf_verify() function in application/core/EA_Security.php performs CSRF token validation but only enforces this check for HTTP POST requests. When a request arrives via GET or other HTTP methods, the function returns early without validating the CSRF token.

This design flaw becomes critical because multiple application endpoints that handle sensitive administrative operations accept input parameters from GET requests or through $_REQUEST (which merges both GET and POST parameters). These state-changing endpoints—such as those responsible for creating administrator accounts, updating user credentials, and modifying system configurations—can be invoked without proper CSRF token validation.

An attacker can exploit this by crafting a malicious URL containing parameters that trigger administrative actions and then tricking an authenticated administrator into clicking the link or visiting a page that loads the malicious request. Since the browser automatically includes session cookies with the request, the application processes it as a legitimate administrative action.

Root Cause

The root cause is improper CSRF protection that fails to enforce token validation across all HTTP methods. The security implementation incorrectly assumes that only POST requests can perform state-changing operations, which violates secure coding principles where CSRF protection should apply universally to any request that modifies application state. Additionally, sensitive endpoints were designed to accept parameters via $_REQUEST instead of strictly limiting input to POST-only parameters with mandatory CSRF validation.

Attack Vector

The attack vector is network-based and requires user interaction. An attacker must first identify administrative endpoints that accept GET parameters for state-changing operations. They then construct a malicious URL containing parameters to create a new admin account or modify an existing administrator's email and password. The attacker delivers this URL to an authenticated administrator through phishing emails, malicious websites, forum posts, or other social engineering techniques. When the victim's browser loads the URL while they have an active session, the request executes with their administrative privileges, allowing the attacker to gain unauthorized access to the system.

The attack does not require direct access to the target system or any special privileges from the attacker's perspective. The victim's authenticated session and browser behavior provide the necessary access for the malicious operations to succeed.

Detection Methods for CVE-2026-23622

Indicators of Compromise

• Unexpected administrator accounts created without corresponding audit trail entries
• Administrative email or password changes without legitimate user activity
• HTTP access logs showing GET requests to administrative endpoints with suspicious parameters
• Unusual referrer headers in access logs indicating requests originating from external domains

Detection Strategies

• Monitor HTTP access logs for GET requests to admin account management endpoints containing user creation or modification parameters
• Implement alerting for administrative account changes and new admin registrations
• Review authentication logs for admin logins from new IP addresses or locations following account modifications
• Analyze web server logs for requests with external referrer headers targeting state-changing endpoints

Monitoring Recommendations

• Enable detailed access logging for all administrative endpoints in Easy!Appointments
• Configure alerts for any changes to administrator credentials or creation of new admin accounts
• Implement monitoring for unusual patterns of GET requests to sensitive application paths
• Review audit logs regularly for administrative actions that lack corresponding user-initiated sessions

How to Mitigate CVE-2026-23622

Immediate Actions Required

• Upgrade Easy!Appointments to a patched version when available from the vendor
• Restrict access to the Easy!Appointments administrative interface to trusted networks or IP addresses
• Review existing administrator accounts for any unauthorized entries and remove suspicious accounts
• Force password resets for all administrative users as a precautionary measure
• Implement Web Application Firewall (WAF) rules to block GET requests with parameters to sensitive administrative endpoints

Patch Information

The vulnerability is tracked in the GitHub Security Advisory GHSA-54v4-4685-vwrj. Organizations should monitor the official Easy!Appointments repository for security updates and apply patches as soon as they become available. The fix should ensure CSRF token validation is enforced for all HTTP methods on state-changing endpoints, not just POST requests.

Workarounds

• Deploy a reverse proxy or WAF to block GET requests containing parameters to administrative endpoints
• Implement network-level access controls to limit administrative interface access to authorized internal networks only
• Configure additional authentication requirements such as IP whitelisting for administrative functions
• Enable HTTP Strict Transport Security (HSTS) and other security headers to reduce attack surface

# Example Apache configuration to block GET requests to admin endpoints
# Add to .htaccess or VirtualHost configuration
<Location "/easyappointments/index.php/backend">
    <LimitExcept POST>
        Require ip 192.168.1.0/24
    </LimitExcept>
</Location>