CVE-2010-0636 in WebCalendar
Summary
by MITRE
Multiple cross-site scripting (XSS) vulnerabilities in WebCalendar 1.2.0, and other versions before 1.2.5, allow remote attackers to inject arbitrary web script or HTML via the (1) tab parameter to users.php and the PATH_INFO to (2) day.php, (3) month.php, and (4) week.php. NOTE: some of these details are obtained from third party information.
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Analysis
by VulDB Data Team • 04/30/2026
The CVE-2010-0636 vulnerability represents a critical cross-site scripting flaw affecting WebCalendar versions prior to 1.2.5, specifically targeting the tab parameter in users.php and PATH_INFO inputs in day.php, month.php, and week.php. This vulnerability falls under CWE-79, which categorizes cross-site scripting as a fundamental web application security weakness where malicious scripts are injected into trusted websites. The vulnerability exploits the application's failure to properly sanitize user input before rendering it in web pages, creating an environment where remote attackers can execute arbitrary JavaScript code in the context of other users' browsers.
The technical exploitation of this vulnerability occurs through multiple attack vectors within the WebCalendar application's parameter handling mechanisms. The tab parameter in users.php serves as an entry point where unvalidated input directly influences the application's output, while the PATH_INFO handling in the calendar view scripts (day.php, month.php, and week.php) creates additional attack surfaces. These flaws demonstrate poor input validation practices and inadequate output encoding, allowing attackers to inject malicious scripts that execute in the victim's browser context. The vulnerability is particularly concerning because it affects core application functionality where users interact with calendar data, making it difficult to distinguish between legitimate and malicious content.
The operational impact of this vulnerability extends beyond simple script execution, as it provides attackers with the capability to perform session hijacking, steal sensitive user credentials, manipulate calendar data, and potentially escalate privileges within the application. Attackers can craft malicious URLs that, when visited by authenticated users, execute scripts that capture session cookies or redirect users to phishing sites. The vulnerability affects all users of the affected WebCalendar versions, making it particularly dangerous in multi-user environments where calendar data contains sensitive personal or business information. According to ATT&CK framework tactic T1566, this vulnerability represents a server-side web application attack that leverages user trust to deliver malicious payloads.
Mitigation strategies for CVE-2010-0636 require immediate implementation of input validation and output encoding measures across all affected parameters. Organizations should upgrade to WebCalendar version 1.2.5 or later, which includes proper sanitization of user inputs and improved parameter handling. Additional defensive measures include implementing Content Security Policy headers to restrict script execution, employing proper input validation routines that filter or escape special characters, and conducting regular security audits of web application input handling. The vulnerability also underscores the importance of secure coding practices, particularly in web applications that process user-supplied data, and aligns with OWASP Top Ten security controls for preventing XSS vulnerabilities through proper input sanitization and output encoding techniques.