CVE-2017-5541 in Symphony
Summary
by MITRE
Directory traversal vulnerability in template/usererror.missing_extension.php in Symphony CMS before 2.6.10 allows remote attackers to rename arbitrary files via a .. (dot dot) in the existing-folder and new-folder parameters.
If you want to get best quality of vulnerability data, you may have to visit VulDB.
Analysis
by VulDB Data Team • 05/14/2026
The vulnerability identified as CVE-2017-5541 represents a critical directory traversal flaw within Symphony CMS versions prior to 2.6.10. This weakness specifically affects the template file usererror.missing_extension.php which handles error reporting scenarios when extensions are missing from the system. The flaw arises from inadequate input validation and sanitization mechanisms that fail to properly restrict directory navigation sequences, allowing malicious actors to exploit the system's file handling capabilities.
The technical implementation of this vulnerability stems from the improper handling of user-supplied parameters within the existing-folder and new-folder fields of the error reporting mechanism. When attackers submit directory traversal sequences using the .. (dot dot) notation through these parameters, the application fails to validate or sanitize the input before processing file operations. This allows adversaries to manipulate the file system path resolution and potentially rename or access arbitrary files within the application's directory structure. The vulnerability operates at the application layer and can be exploited remotely without requiring authentication, making it particularly dangerous for publicly accessible web applications.
The operational impact of this vulnerability extends beyond simple file access restrictions and can enable attackers to perform arbitrary file operations including renaming, deleting, or potentially overwriting critical system files. Given that Symphony CMS is a content management system, successful exploitation could lead to complete system compromise, data exfiltration, or the installation of malicious payloads. The vulnerability's remote exploitability means that attackers can leverage this flaw from external networks, potentially affecting multiple users and systems without requiring physical access or prior system compromise. This type of vulnerability aligns with CWE-22 - Improper Limitation of a Pathname to a Restricted Directory and is categorized under the ATT&CK framework as part of the privilege escalation and persistence techniques.
Mitigation strategies for this vulnerability require immediate patching of Symphony CMS installations to version 2.6.10 or later where the directory traversal protections have been implemented. Organizations should also implement input validation mechanisms that sanitize all user-supplied parameters, particularly those used in file system operations. Additional protective measures include implementing proper access controls and privilege separation, monitoring for suspicious file operations, and conducting regular security assessments of web applications. The fix typically involves implementing proper path validation that prevents directory traversal sequences from being processed in file system operations, ensuring that all user inputs are properly validated against a whitelist of acceptable characters and patterns.