CVE-2018-6842 in Kentico
Summary
by MITRE
Kentico 10 before 10.0.50 and 11 before 11.0.3 has XSS in which a crafted URL results in improper construction of a system page.
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Analysis
by VulDB Data Team • 12/19/2025
The vulnerability identified as CVE-2018-6842 affects Kentico content management systems version 10 before 10.0.50 and version 11 before 11.0.3, representing a cross-site scripting flaw that emerges from improper URL handling within system page construction. This issue stems from the application's insufficient sanitization of user-supplied input parameters that are incorporated into URL structures used for generating system pages. The vulnerability manifests when crafted malicious URLs are processed by the CMS, leading to the injection of malicious scripts into the system-generated pages. The flaw resides in the manner in which the application constructs URLs for internal system pages without adequate validation or encoding of input parameters, creating an environment where attacker-controlled data can be seamlessly integrated into the page generation process.
The technical implementation of this vulnerability demonstrates a classic cross-site scripting vector through URL parameter manipulation, where user-provided values are directly embedded into system-generated content without proper context-aware encoding or validation. When the CMS processes a specially crafted URL containing malicious input, the system fails to properly escape or validate the parameters before incorporating them into the HTML output of system pages. This allows an attacker to inject malicious JavaScript code that executes in the context of other users' browsers who visit the affected pages. The vulnerability specifically impacts the system page construction mechanism where URLs are dynamically assembled, making it particularly dangerous as it can affect administrative interfaces and system-generated content that users trust. According to CWE standards, this represents a CWE-79: Cross-site Scripting vulnerability, with the specific manifestation falling under CWE-116: Improper Encoding or Escaping of Output and CWE-601: URL Redirection to Untrusted Site.
The operational impact of this vulnerability extends beyond simple script injection, as it can enable attackers to perform session hijacking, deface system pages, steal sensitive administrative credentials, or redirect users to malicious sites. The attack surface is particularly concerning because system pages often contain sensitive administrative functions and user information that could be compromised. An attacker could exploit this vulnerability to gain unauthorized access to administrative interfaces, potentially leading to complete system compromise. The vulnerability affects both version 10 and 11 of the CMS, indicating a widespread issue across multiple releases that could impact numerous organizations running these outdated versions. The exploitability of this vulnerability is relatively high since it requires minimal user interaction beyond visiting a maliciously crafted URL, making it particularly dangerous in environments where users might inadvertently encounter such links through phishing campaigns or compromised websites.
Organizations affected by this vulnerability should prioritize immediate patching of their Kentico installations to versions 10.0.50 and 11.0.3 respectively, which contain the necessary fixes for the URL parameter sanitization issues. Network administrators should implement URL filtering and monitoring solutions to detect and block suspicious URL patterns that could be used to exploit this vulnerability. The mitigation strategy should include input validation at all points where user-supplied data is processed, particularly for URL parameters that are used in system page construction. Additionally, implementing proper output encoding for all dynamic content, especially in administrative interfaces, can help prevent the execution of injected scripts. Security teams should also consider implementing web application firewalls with rules specifically designed to detect and block XSS attack patterns in URL parameters. According to ATT&CK framework, this vulnerability maps to T1059.007: Command and Scripting Interpreter: JavaScript, as it enables execution of malicious javascript code, and T1566.001: Credential Access: Phishing, since the vulnerability can be exploited through phishing campaigns targeting system administrators. The vulnerability also aligns with T1213.002: Data from Information Repositories: Database Injection, as the compromised system pages could potentially expose sensitive data through the execution of malicious scripts.