CVE-2018-19918 in CuppaCMS
Summary
by MITRE
CuppaCMS has XSS via an SVG document uploaded to the administrator/#/component/table_manager/view/cu_views URI.
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Analysis
by VulDB Data Team • 05/06/2025
CVE-2018-19918 represents a cross-site scripting vulnerability within CuppaCMS that exploits insecure file upload handling mechanisms. This vulnerability specifically affects the administrator interface where users can manage components through the table_manager/view/cu_views URI endpoint. The flaw occurs when SVG documents are uploaded to this location without proper validation or sanitization, allowing malicious actors to inject malicious scripts that execute in the context of other users' browsers. The vulnerability falls under CWE-79 which categorizes cross-site scripting as a critical web application security weakness, and aligns with ATT&CK technique T1566.001 for initial access through malicious file uploads.
The technical implementation of this vulnerability stems from inadequate input validation and output encoding practices within the CMS upload functionality. When administrators or users upload SVG files through the designated URI, the application fails to properly sanitize or validate the content, particularly the embedded script elements within SVG markup. SVG files can contain executable JavaScript through various mechanisms including the <script> tag, event handlers, and external references. This creates an attack surface where malicious actors can craft SVG files containing malicious payloads that persist within the application's file system and execute when viewed by authenticated users with administrative privileges.
The operational impact of this vulnerability extends beyond simple script execution as it provides attackers with potential access to administrative functions and sensitive data. When successful, the XSS attack can lead to session hijacking, privilege escalation, and full administrative control over the CMS. Attackers can leverage this vulnerability to steal session cookies, modify content, create new user accounts, or even execute commands on the underlying server if additional vulnerabilities exist. The attack requires minimal user interaction since the malicious SVG is served through the legitimate administration interface, making it particularly dangerous for targeted attacks against CMS administrators who regularly access these components.
Mitigation strategies for CVE-2018-19918 should focus on implementing robust input validation and content sanitization measures. Organizations should enforce strict file type validation that rejects SVG uploads or applies comprehensive sanitization to all uploaded files, particularly those that may contain executable content. The implementation should include removing or neutralizing script elements from SVG files during upload processing, implementing proper content security policies to prevent script execution, and applying the principle of least privilege to limit administrative access. Security controls should also include regular security scanning and monitoring for unauthorized file uploads, with network segmentation to limit access to administration interfaces. Additionally, implementing web application firewalls with signature-based detection for known XSS patterns can provide additional protection layers. The vulnerability demonstrates the critical importance of validating and sanitizing all user-supplied content, particularly in web applications that handle file uploads, as highlighted by industry best practices for secure coding and OWASP Top 10 security recommendations.