CVE-2017-15235 in Horde Groupware
Summary
by MITRE
The File Manager (gollem) module 3.0.11 in Horde Groupware 5.2.21 allows remote attackers to bypass Horde authentication for file downloads via a crafted fn parameter that corresponds to the exact filename.
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Analysis
by VulDB Data Team • 09/06/2025
The vulnerability identified as CVE-2017-15235 affects the File Manager module known as gollem within Horde Groupware version 5.2.21. This represents a critical authentication bypass flaw that enables remote attackers to access protected files without proper credentials. The vulnerability specifically resides in the handling of the fn parameter, which controls file download operations within the file manager interface. When a malicious actor crafts a specially formatted fn parameter that exactly matches a target filename, the system fails to properly verify authentication status before allowing file access.
This authentication bypass vulnerability operates through a path traversal or direct file access mechanism where the gollem module does not adequately validate user permissions or session authenticity when processing file download requests. The flaw essentially allows an attacker to circumvent the normal authentication flow by directly specifying filenames in the fn parameter, effectively bypassing the security controls that should normally require valid user credentials and proper authorization before granting access to file resources. The vulnerability is particularly dangerous because it operates at the application level rather than network level, making it more difficult to detect and prevent through traditional network security measures.
The operational impact of this vulnerability extends beyond simple unauthorized file access, as it can potentially lead to data exfiltration, system compromise, and unauthorized access to sensitive information stored within the Horde Groupware environment. Attackers could leverage this flaw to access confidential documents, user data, or system files that should normally be protected by the authentication system. The vulnerability affects the core file management functionality of the application, potentially exposing all files that are accessible through the gollem module to unauthorized access. This represents a significant risk to organizations relying on Horde Groupware for collaboration and file management services.
From a cybersecurity perspective, this vulnerability aligns with CWE-287 which addresses improper authentication issues in software systems. The flaw demonstrates a classic case of insufficient authorization checks where the application fails to properly verify that the requesting user has appropriate permissions to access the specified resource. Security professionals should note the ATT&CK technique T1078 which covers valid accounts and legitimate credentials for lateral movement, as this vulnerability essentially allows attackers to leverage valid file names to bypass authentication requirements. Organizations should implement immediate mitigations including updating to patched versions of Horde Groupware, implementing additional access controls, and monitoring for suspicious file access patterns. The vulnerability also highlights the importance of proper input validation and authentication flow implementation in web applications, particularly those handling file operations and user data access.