CVE-2019-20389 in Subrion
Summary
by MITRE
An XSS issue was identified on the Subrion CMS 4.2.1 /panel/configuration/general settings page. A remote attacker can inject arbitrary JavaScript code in the v[language_switch] parameter (within multipart/form-data), which is reflected back within a user's browser without proper output encoding.
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Analysis
by VulDB Data Team • 05/16/2020
The vulnerability identified in CVE-2019-20389 represents a classic cross-site scripting flaw within the Subrion CMS 4.2.1 administration interface. This issue specifically targets the /panel/configuration/general settings page where user input is improperly sanitized before being rendered back to the browser. The vulnerability manifests when an attacker manipulates the v[language_switch] parameter through multipart/form-data requests, allowing malicious JavaScript code execution in the context of a victim's browser session. The flaw demonstrates a critical failure in input validation and output encoding practices that directly violates fundamental web security principles.
The technical implementation of this vulnerability stems from the application's failure to properly encode or sanitize user-supplied data before rendering it within the HTML response. When the v[language_switch] parameter is submitted through the multipart/form-data format, the CMS does not adequately filter or escape the input before incorporating it into the page's HTML structure. This reflection pattern creates an ideal environment for XSS exploitation where attacker-controlled code can execute with the privileges of the authenticated user. The vulnerability is particularly concerning because it occurs within the administrative panel, potentially allowing attackers to escalate privileges or gain unauthorized access to sensitive system configurations. According to CWE classification, this represents a CWE-79: Cross-site Scripting vulnerability, specifically categorized as a reflected XSS attack vector that lacks proper output encoding mechanisms.
The operational impact of this vulnerability extends beyond simple script execution as it provides attackers with potential access to administrative functions within the CMS. An attacker could craft malicious payloads that redirect users to phishing sites, steal session cookies, or manipulate configuration settings that could compromise the entire content management system. The reflected nature of this vulnerability means that attacks can be delivered through various vectors including email links or compromised websites that direct users to the vulnerable page. This creates a significant risk for organizations using Subrion CMS 4.2.1 as attackers could exploit this vulnerability to perform unauthorized modifications to website content or steal administrative credentials. The vulnerability aligns with ATT&CK technique T1213.002 for credential access through web application vulnerabilities and T1566 for social engineering attacks leveraging reflected XSS.
Mitigation strategies for CVE-2019-20389 should prioritize immediate implementation of proper input validation and output encoding measures. Organizations must ensure that all user-supplied parameters, particularly those used in administrative interfaces, undergo strict sanitization before being processed or rendered. The implementation of Content Security Policy headers and proper HTML encoding of dynamic content can significantly reduce the attack surface. Additionally, upgrading to Subrion CMS versions that have addressed this vulnerability is essential as the original 4.2.1 release contains insufficient security controls. Security teams should also implement regular input validation testing and monitor for unusual parameter submissions within administrative interfaces. The vulnerability highlights the importance of applying the principle of least privilege in web applications and demonstrates why comprehensive security testing, including dynamic application security testing, should be integrated into development lifecycle processes. Organizations should also consider implementing web application firewalls to detect and block suspicious multipart/form-data requests that attempt to exploit such XSS vulnerabilities.