CVE-2018-9126 in DNNArticle Module
Summary
by MITRE
The DNNArticle module 11 for DNN (formerly DotNetNuke) allows remote attackers to read the web.config file, and consequently discover database credentials, via the /GetCSS.ashx/?CP=%2fweb.config URI.
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Analysis
by VulDB Data Team • 11/10/2025
The vulnerability identified as CVE-2018-9126 affects the DNNArticle module version 11 within the DNN (formerly DotNetNuke) platform, representing a critical information disclosure flaw that enables remote attackers to access sensitive configuration files. This vulnerability resides in the module's handling of the GetCSS.ashx endpoint, which processes the CP parameter without adequate input validation or access control measures. The attack vector specifically targets the /GetCSS.ashx/?CP=%2fweb.config URI pattern, where the encoded forward slash (%2f) allows an attacker to traverse the file system and retrieve the web.config file from the server's root directory. The web.config file contains critical application configuration data including database connection strings, encryption keys, and other sensitive credentials that are essential for the application's operation and security posture. This flaw directly violates the principle of least privilege and demonstrates a lack of proper input sanitization and file access controls that are fundamental to secure application development practices.
The technical exploitation of this vulnerability occurs through a simple HTTP GET request that leverages path traversal mechanisms within the DNNArticle module's file handling logic. When the module processes the CP parameter containing the path traversal sequence, it fails to validate or sanitize the input before using it to access the file system. This creates an arbitrary file reading condition that allows attackers to retrieve any file accessible to the web application's process, with web.config being the most critical target due to its inclusion of database credentials and other sensitive configuration data. The vulnerability is classified as a path traversal or directory traversal issue, which maps to CWE-22 in the Common Weakness Enumeration catalog, specifically representing an insufficient input validation weakness that allows attackers to manipulate file access paths. The attack requires no authentication or privileged access, making it particularly dangerous as it can be exploited by any remote user with access to the vulnerable DNN instance.
The operational impact of this vulnerability extends far beyond simple information disclosure, as the exposure of database credentials provides attackers with direct access to the underlying database systems that store application data, user information, and potentially sensitive business data. Once attackers obtain the database connection strings, they can establish direct database connections and potentially escalate their privileges to perform unauthorized data manipulation, extraction, or deletion operations. This vulnerability creates a gateway for more severe attacks including data breaches, database compromise, and potential lateral movement within the network infrastructure. The exposure of encryption keys and other configuration parameters could also enable attackers to decrypt sensitive data or impersonate legitimate application services. From an ATT&CK framework perspective, this vulnerability maps to techniques such as T1083 (File and Directory Discovery) and T1566 (Phishing for Information) as attackers can systematically explore the file system to locate and extract sensitive information. The vulnerability also represents a failure in the application's defense in depth principles, as proper access controls and input validation should have prevented the unauthorized file access regardless of the module's functionality.
Mitigation strategies for CVE-2018-9126 should include immediate patching of the DNNArticle module to version 11.02.00 or later, which addresses the path traversal vulnerability through proper input validation and access control mechanisms. Organizations should also implement network-level restrictions to limit access to the vulnerable endpoints and consider implementing web application firewalls that can detect and block path traversal attempts. Additionally, the principle of least privilege should be enforced by ensuring that the web application has minimal file system access rights and that sensitive configuration files are stored outside the web root directory. Regular security assessments and input validation testing should be conducted to identify similar vulnerabilities in other modules or custom applications. The vulnerability highlights the importance of secure coding practices and the necessity of implementing proper parameter validation, access control checks, and secure file handling mechanisms as recommended by industry standards such as the OWASP Top Ten and NIST cybersecurity guidelines. Organizations should also consider implementing automated vulnerability scanning and continuous monitoring to detect similar path traversal vulnerabilities across their entire application portfolio.