CVE-2018-16655 in Gxlcms
Summary
by MITRE
Gxlcms 1.0 has XSS via the PATH_INFO to gx/lib/ThinkPHP/Tpl/ThinkException.tpl.php.
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Analysis
by VulDB Data Team • 03/21/2020
The vulnerability identified as CVE-2018-16655 affects Gxlcms version 1.0 and represents a cross-site scripting flaw that exists within the application's handling of PATH_INFO parameters. This issue manifests specifically in the gx/lib/ThinkPHP/Tpl/ThinkException.tpl.php file, where user-supplied input is not properly sanitized before being rendered in the web application's error handling template. The vulnerability stems from the application's failure to validate or escape input data that flows through the PATH_INFO server variable, which is commonly used in PHP applications to pass additional path information to scripts. When an attacker crafts malicious input through this parameter and the application encounters an error condition, the unescaped data gets embedded directly into the HTML output of the error template, creating an exploitable XSS vector.
The technical implementation of this vulnerability follows the typical pattern of reflected cross-site scripting attacks where malicious payloads are injected through URL parameters or server variables and then executed in the context of other users' browsers. In this case, the PATH_INFO variable serves as the injection point, which is processed by the ThinkPHP framework's error handling mechanism. The vulnerability is particularly concerning because it occurs within the application's error template processing, meaning that even legitimate error conditions could become attack vectors when malicious input is present. The flaw allows attackers to execute arbitrary JavaScript code in victims' browsers, potentially leading to session hijacking, credential theft, or redirection to malicious sites. This type of vulnerability aligns with CWE-79 which specifically addresses cross-site scripting flaws in web applications.
The operational impact of CVE-2018-16655 extends beyond simple script execution as it represents a fundamental security weakness in how the application handles error conditions and user input validation. Attackers can exploit this vulnerability without requiring authentication or specific privileges, making it particularly dangerous in environments where the application is publicly accessible. The vulnerability could be leveraged to steal session cookies, redirect users to phishing sites, or perform actions on behalf of authenticated users if they are logged in. Given that this affects the ThinkPHP framework's error handling component, the impact is amplified as it could potentially affect multiple applications using the same framework version. The vulnerability demonstrates poor input validation practices and highlights the critical importance of sanitizing all user-supplied data, especially in server variables that are commonly used for routing and path information.
Mitigation strategies for this vulnerability must address both the immediate code-level issues and broader architectural security practices. The primary fix involves implementing proper input sanitization and output escaping mechanisms within the error handling template, specifically in the ThinkException.tpl.php file. All user-supplied data that flows into template rendering should be properly escaped using context-appropriate escaping functions such as htmlspecialchars in PHP. Additionally, developers should implement proper validation of PATH_INFO parameters and consider implementing Content Security Policy headers to limit the execution of unauthorized scripts. Organizations should also conduct comprehensive security reviews of their applications to identify similar patterns in error handling and input processing. The vulnerability underscores the necessity of following secure coding practices and adhering to the principle of least privilege in web application development, which is consistent with ATT&CK technique T1059.007 for script injection and T1566 for social engineering through malicious links. Regular security testing including dynamic application security testing and static code analysis should be implemented to prevent similar vulnerabilities from being introduced in future versions.