CVE-2019-11537 in osTicket
Summary
by MITRE
In osTicket before 1.12, XSS exists via /upload/file.php, /upload/scp/users.php?do=import-users, and /upload/scp/ajax.php/users/import if an agent manager user uploads a crafted .csv file to the User Importer, because file contents can appear in an error message. The XSS can lead to local file inclusion.
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Analysis
by VulDB Data Team • 09/06/2025
The vulnerability identified as CVE-2019-11537 affects osTicket versions prior to 1.12 and represents a critical cross-site scripting weakness that can be exploited through multiple upload endpoints including file.php, scp/users.php, and scp/ajax.php/users/import. This vulnerability specifically targets the User Importer functionality where agent manager users can upload crafted csv files, creating a dangerous attack vector that combines multiple security flaws. The vulnerability stems from insufficient input validation and output encoding mechanisms within the application's file processing routines, allowing malicious payloads to be executed when error messages are displayed to users. This flaw falls under CWE-79 which specifically addresses cross-site scripting vulnerabilities in web applications, and aligns with ATT&CK technique T1203 which covers exploitation of web application vulnerabilities for code execution.
The technical implementation of this vulnerability occurs when a malicious user with agent manager privileges uploads a specially crafted csv file that contains javascript code within its content. When the system processes this file and encounters errors during the import process, the malformed content gets reflected back in error messages without proper sanitization or encoding. The reflected javascript code can then execute in the context of other users' browsers who view these error messages, enabling attackers to perform session hijacking, defacement, or data exfiltration. The vulnerability becomes particularly dangerous when combined with local file inclusion capabilities, as the reflected XSS can be leveraged to establish persistent access to the system.
The operational impact of CVE-2019-11537 extends beyond simple XSS execution and represents a significant threat to organizational security infrastructure. Attackers can exploit this vulnerability to escalate privileges, gain unauthorized access to sensitive customer data, and potentially compromise entire systems through the chained local file inclusion attack. The attack requires minimal privileges since it targets the agent manager role, which is commonly granted to support staff members within help desk environments. This makes the vulnerability particularly dangerous in organizations where help desk staff have elevated access rights. The vulnerability affects the core functionality of osTicket's user management system and can result in unauthorized data access, privacy violations, and potential system compromise.
Mitigation strategies for this vulnerability should focus on immediate patching of the osTicket application to version 1.12 or later where the issue has been resolved through proper input validation and output encoding. Organizations should implement strict file validation mechanisms that sanitize all uploaded content and prevent javascript execution within file contents. Network segmentation and access controls should be strengthened to limit agent manager privileges to only essential functions. Additionally, implementing web application firewalls with XSS detection capabilities and regular security monitoring can help identify and prevent exploitation attempts. The remediation process should include comprehensive testing of file upload functionality and validation of error message handling to ensure no similar vulnerabilities exist in related components. Security awareness training for support staff regarding file upload risks and proper privilege management should also be implemented to reduce the attack surface.