CVE-2008-6736 in Flat Calendar
Summary
by MITRE
Flat Calendar 1.1 does not properly restrict access to administrative functions, which allows remote attackers to (1) add new events via calAdd.php, as reachable from admin/add.php, or (2) delete events via admin/deleteEvent.php. NOTE: this is only a vulnerability when the administrator does not follow recommendations in the product s security documentation.
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Analysis
by VulDB Data Team • 06/25/2025
The vulnerability identified as CVE-2008-6736 affects Flat Calendar version 1.1, a web-based calendar application that fails to implement proper access controls for administrative functions. This weakness stems from inadequate authentication and authorization mechanisms within the application's codebase, specifically in the calAdd.php and admin/deleteEvent.php components. The flaw represents a critical security oversight that directly violates fundamental web application security principles and can be categorized under CWE-285: "Improper Authorization" within the Common Weakness Enumeration framework.
The technical implementation of this vulnerability allows remote attackers to bypass normal access restrictions through two primary attack vectors. The first vector involves exploiting the calAdd.php script which can be accessed directly from the admin/add.php endpoint, enabling unauthorized users to add new calendar events without proper administrative credentials. The second vector targets the admin/deleteEvent.php component, permitting arbitrary event deletion through remote exploitation. Both attack paths demonstrate a complete breakdown in the application's privilege management system, where the lack of proper session validation and user role verification creates persistent backdoors for malicious actors.
From an operational perspective, this vulnerability exposes organizations to significant risks including data integrity compromise, unauthorized content modification, and potential disruption of calendar services. The impact extends beyond simple event manipulation to encompass broader security implications such as information disclosure and service availability concerns. Attackers can leverage this weakness to inject malicious content into calendar systems, potentially using the calendar as a staging ground for further attacks or to establish persistence within network environments. The vulnerability's severity is amplified by its remote exploitability, eliminating the need for physical access or local network presence.
The vulnerability's classification aligns with ATT&CK technique T1078.004: "Valid Accounts: Cloud Accounts" and T1566.002: "Phishing: Spearphishing Attachment" as attackers can potentially use this weakness to establish unauthorized administrative presence within calendar systems. Organizations should implement immediate mitigations including enforcing proper access controls through robust authentication mechanisms, implementing role-based access controls, and ensuring all administrative endpoints require proper session validation. The recommended approach involves implementing input validation, output encoding, and proper access control checks at all entry points to administrative functions, following security best practices outlined in OWASP Top 10 and NIST SP 800-53 security frameworks. Additionally, organizations must ensure that all administrative functions are protected by proper authorization checks and that default configurations do not expose administrative interfaces to unauthorized users.