CVE-2004-1510

Vulnerability

WebCalendar versions prior to the fix are vulnerable to privilege escalation via parameter tampering. The scripts view_entry.php and upcoming.php accept critical parameters (such as user identifiers or event IDs) without proper validation. An attacker can modify these parameters to access or modify data belonging to other users, effectively elevating their privileges. The exact affected versions are not specified in the available references, but the vulnerability was reported in 2004 [1].

Exploitation

An attacker needs only network access to the WebCalendar application. No authentication is required if the vulnerable scripts are publicly accessible. By crafting HTTP requests to view_entry.php or upcoming.php with altered parameter values (e.g., changing a user parameter to another user's ID), the attacker can impersonate that user or gain unauthorized access to their calendar data. The attack does not require user interaction or any special privileges [1].

Impact

Successful exploitation allows an attacker to gain the privileges of another user. This can lead to unauthorized viewing, modification, or deletion of calendar entries, as well as potential access to sensitive information stored in the application. The attacker effectively bypasses access controls and can perform actions as the targeted user [1].

Mitigation

The vendor released a fixed version of WebCalendar after the disclosure. Users should upgrade to the latest version available from the official WebCalendar website. If upgrading is not immediately possible, administrators should restrict access to the vulnerable scripts (e.g., via .htaccess or firewall rules) and ensure that sensitive parameters are validated server-side. The vulnerability is not listed on the CISA Known Exploited Vulnerabilities (KEV) catalog [1].