CVE-2012-5566 in IMP Webmail
Summary
by MITRE
Multiple cross-site scripting (XSS) vulnerabilities in Horde Kronolith Calendar Application H4 before 3.0.17, as used in Horde Groupware Webmail Edition before 4.0.8, allow remote attackers to inject arbitrary web script or HTML via the (1) tasks view or (2) search view.
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Analysis
by VulDB Data Team • 05/09/2026
The CVE-2012-5566 vulnerability represents a critical cross-site scripting flaw in the Horde Kronolith calendar application, specifically affecting versions prior to H4 3.0.17 and Horde Groupware Webmail Edition before 4.0.8. This vulnerability exposes web applications to persistent threats where malicious actors can inject arbitrary web scripts or HTML content into user sessions. The flaw manifests in two primary attack vectors: the tasks view and the search view of the calendar application, making it particularly dangerous as it targets commonly used interface components. The vulnerability falls under CWE-79, which specifically addresses cross-site scripting attacks, and aligns with ATT&CK technique T1059.008 for command and scripting interpreter. The affected applications are widely deployed in enterprise environments and webmail systems, where calendar functionality is frequently accessed by multiple users, amplifying the potential impact of such an exploit.
The technical implementation of this vulnerability stems from inadequate input validation and output sanitization within the calendar application's user interface components. When users navigate to the tasks view or search view, the application fails to properly sanitize user-supplied data before rendering it in the browser context. This allows attackers to craft malicious payloads that, when processed by the application, execute in the context of other users' browsers. The vulnerability is particularly concerning because it affects the core calendar functionality that users interact with regularly, providing attackers with persistent access vectors. The flaw enables attackers to steal session cookies, redirect users to malicious sites, or perform actions on behalf of authenticated users, potentially leading to complete account compromise and unauthorized access to sensitive calendar data.
The operational impact of CVE-2012-5566 extends beyond simple data theft or defacement, as it creates persistent backdoors within calendar applications that can be exploited for extended periods. Organizations using affected versions of Horde Groupware Webmail Edition face significant risks including unauthorized access to personal and business calendars, potential data exfiltration, and the possibility of lateral movement within network environments. The vulnerability's persistence is particularly dangerous as it allows attackers to maintain access across multiple user sessions without requiring repeated exploitation attempts. Security teams must consider the potential for credential theft, as attackers can capture authentication tokens and session information from calendar applications. The attack surface is further expanded due to the widespread adoption of Horde applications in corporate environments, making this vulnerability particularly attractive to threat actors seeking to establish long-term presence within target organizations.
Mitigation strategies for CVE-2012-5566 require immediate patching of affected applications to version 3.0.17 or later for Kronolith and 4.0.8 or later for Horde Groupware Webmail Edition. Organizations should implement comprehensive input validation and output encoding measures across all user-facing interfaces, particularly in calendar and task management components. Network segmentation and web application firewalls can provide additional layers of protection by monitoring and filtering malicious traffic patterns. Security teams should conduct thorough vulnerability assessments to identify any other potentially affected applications within their infrastructure and implement regular security testing procedures. The remediation process must include thorough testing of patches to ensure compatibility with existing system configurations while maintaining application functionality. Additionally, user education regarding suspicious calendar entries and search results should be implemented as part of broader security awareness programs. Organizations should also consider implementing content security policies and monitoring for anomalous user behavior patterns that might indicate exploitation attempts.