CVE-2026-24636: Sugar Calendar Auth Bypass Vulnerability

CVE-2026-24636 Overview

CVE-2026-24636 is a Missing Authorization vulnerability (CWE-862) discovered in the Sugar Calendar (Lite) WordPress plugin developed by Syed Balkhi. This broken access control vulnerability allows authenticated attackers with low privileges to exploit incorrectly configured access control security levels, potentially gaining unauthorized access to sensitive calendar data and functionality.

The vulnerability stems from insufficient authorization checks within the plugin's functionality, enabling users with minimal permissions to access resources or perform actions that should be restricted to higher-privileged users such as administrators.

Critical Impact

Authenticated users with low-level privileges can bypass access controls to read sensitive information from the calendar system, potentially exposing private event data and user information.

Affected Products

• Sugar Calendar (Lite) plugin for WordPress versions up to and including 3.10.1
• WordPress installations using the sugar-calendar-lite plugin

Discovery Timeline

• 2026-01-23 - CVE-2026-24636 published to NVD
• 2026-01-26 - Last updated in NVD database

Technical Details for CVE-2026-24636

Vulnerability Analysis

This vulnerability is classified as Missing Authorization (CWE-862), which occurs when software does not perform proper authorization checks to verify that a user has permission to access a resource or perform an action. In the context of the Sugar Calendar (Lite) plugin, the vulnerability allows authenticated users to bypass intended access restrictions.

The flaw exists in how the plugin handles user permissions for certain calendar-related operations. When a user attempts to access specific functionality or data, the plugin fails to properly verify whether the requesting user has the necessary privileges, resulting in unauthorized information disclosure.

WordPress plugins that implement their own access control mechanisms outside of WordPress's native capability system are particularly susceptible to this type of vulnerability. The broken access control allows privilege escalation within the plugin's scope, potentially exposing calendar events, schedules, and associated metadata to unauthorized users.

Root Cause

The root cause of CVE-2026-24636 is the absence of proper authorization checks in the Sugar Calendar (Lite) plugin's code paths. Rather than verifying user capabilities before granting access to protected resources, the plugin relies on incorrectly configured or missing access control enforcement, allowing any authenticated user to access restricted functionality regardless of their assigned role.

This typically occurs when developers assume that authentication alone is sufficient security, neglecting the critical distinction between authentication (who you are) and authorization (what you're allowed to do).

Attack Vector

The attack is network-based and requires the attacker to have low-level authenticated access to the WordPress installation (such as a subscriber account). Once authenticated, the attacker can exploit the missing authorization checks to access calendar data or functionality that should be restricted to administrators or editors.

The vulnerability can be exploited remotely over the network without any user interaction required. However, the impact is limited to information disclosure (confidentiality breach) without direct integrity or availability implications according to the vulnerability assessment.

For detailed technical information about this vulnerability, refer to the Patchstack Vulnerability Advisory.

Detection Methods for CVE-2026-24636

Indicators of Compromise

• Unusual access patterns to calendar-related API endpoints from low-privileged users
• Unexpected AJAX requests to Sugar Calendar plugin functions from subscriber-level accounts
• Log entries showing access to calendar administrative functions by non-administrative users
• Anomalous data access patterns in WordPress audit logs related to the sugar-calendar-lite plugin

Detection Strategies

• Monitor WordPress access logs for unauthorized requests to Sugar Calendar plugin endpoints
• Implement user activity monitoring to detect subscribers or contributors accessing calendar data outside their permission scope
• Deploy Web Application Firewall (WAF) rules to detect and block exploitation attempts targeting broken access control patterns
• Enable detailed WordPress audit logging to capture all plugin-related access attempts

Monitoring Recommendations

• Review and audit user access logs regularly for suspicious activity involving calendar functionality
• Implement real-time alerting for access control violations within the WordPress environment
• Monitor for bulk data access or enumeration attempts against calendar endpoints
• Deploy endpoint detection solutions to identify post-exploitation activity on WordPress servers

How to Mitigate CVE-2026-24636

Immediate Actions Required

• Update Sugar Calendar (Lite) plugin to the latest patched version immediately
• Audit current user roles and permissions on WordPress installations using this plugin
• Review access logs for any signs of exploitation prior to patching
• Consider temporarily disabling the plugin if an immediate update is not possible
• Implement additional access controls at the web server or WAF level

Patch Information

Site administrators should update the Sugar Calendar (Lite) plugin to a version newer than 3.10.1 that addresses this vulnerability. Check the official WordPress plugin repository or the Patchstack advisory for the latest security update information.

Before applying the patch, ensure you have a complete backup of your WordPress installation and database. After updating, verify that the calendar functionality works as expected and that proper access controls are now enforced.

Workarounds

• Restrict subscriber and contributor account creation until the plugin is patched
• Implement IP-based access restrictions for the WordPress admin area
• Use a WordPress security plugin to add additional capability checks at the application layer
• Consider using a Web Application Firewall to filter malicious requests targeting the vulnerable endpoints

# WordPress CLI command to update the plugin
wp plugin update sugar-calendar-lite --force

# Verify current plugin version
wp plugin get sugar-calendar-lite --field=version

# List users with potential access to exploit
wp user list --role=subscriber --format=table