CVE-2018-19599 in Monstra
Summary
by MITRE
Monstra CMS 1.6 allows XSS via an uploaded SVG document to the admin/index.php?id=filesmanager&path=uploads/ URI. NOTE: this is a discontinued product.
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Analysis
by VulDB Data Team • 05/10/2025
The vulnerability CVE-2018-19599 represents a cross-site scripting flaw discovered in Monstra CMS version 1.6 that specifically affects the file management functionality. This issue arises from inadequate input validation and sanitization when processing uploaded SVG files through the administrative interface. The vulnerability exists within the filesmanager component that handles file uploads and displays them in the web interface, creating a persistent XSS vector that can be exploited by attackers who gain access to the administrative account or can upload malicious content.
The technical implementation of this vulnerability stems from the CMS's failure to properly sanitize SVG file contents before rendering them in the browser context. When an attacker uploads a specially crafted SVG document to the uploads directory through the admin interface, the system stores and displays the file without adequate security measures to prevent malicious script execution. The affected URI path admin/index.php?id=filesmanager&path=uploads/ provides direct access to the file management system where the vulnerable SVG handling occurs. This particular implementation allows attackers to inject malicious JavaScript code that executes in the context of authenticated admin sessions, potentially enabling complete system compromise.
The operational impact of this vulnerability extends beyond simple XSS execution as it represents a critical security flaw that can be leveraged for privilege escalation and persistent access to the CMS administration interface. Attackers can use this vulnerability to execute arbitrary code within the context of the administrative user's session, potentially leading to full system compromise, data exfiltration, or the deployment of backdoors. The vulnerability's exploitation requires minimal privileges since it targets the administrative upload functionality, making it particularly dangerous for systems where administrators have elevated access rights. This flaw directly maps to CWE-79 which defines cross-site scripting vulnerabilities in web applications.
Security professionals should note that this vulnerability demonstrates poor input validation and output encoding practices within the CMS's file handling system. The attack surface is expanded by the fact that SVG files are often treated as safe content due to their image format nature, but the CMS fails to properly validate the script content within these files. The vulnerability also aligns with ATT&CK technique T1059.007 which covers scripting languages and T1566 which covers credential access through phishing and social engineering. Organizations should consider implementing Content Security Policy headers as a defensive measure and ensure that all file upload mechanisms properly validate file types and content. Additionally, regular security audits of deprecated software systems are crucial since Monstra CMS is no longer maintained, making such vulnerabilities particularly dangerous.
The exploitation of this vulnerability requires an attacker to either gain administrative access or find a way to upload malicious content through a legitimate administrative session. This makes the attack vector particularly concerning as it can be combined with other vulnerabilities or social engineering techniques to achieve system compromise. The lack of ongoing security updates for Monstra CMS means that this vulnerability remains unpatched and exploitable in systems that have not migrated to supported alternatives. Organizations should prioritize immediate migration from deprecated CMS platforms and implement robust file validation mechanisms to prevent similar vulnerabilities in their own applications. The vulnerability serves as a reminder of the importance of proper security controls even in seemingly benign functionality like file uploads, where the combination of user input and web rendering creates significant attack surface.