CVE-2018-5216 in Radiant
Summary
by MITRE
Radiant CMS 1.1.4 has XSS via crafted Markdown input in the part_body_content parameter to an admin/pages/*/edit resource.
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Analysis
by VulDB Data Team • 01/05/2018
The vulnerability CVE-2018-5216 represents a cross-site scripting flaw discovered in Radiant CMS version 1.1.4 that specifically targets the administrative interface. This issue manifests when malicious users submit crafted markdown content through the part_body_content parameter within the admin/pages/*/edit resource path. The vulnerability arises from insufficient input sanitization and output encoding mechanisms that fail to properly handle potentially malicious markdown syntax. The affected parameter exists within the content management system's administrative editing functionality, where users can modify page content through markdown formatting. This particular vulnerability falls under the CWE-79 category of Cross-Site Scripting, specifically representing a stored XSS variant since the malicious content is persisted within the CMS database and can affect multiple users who view the affected page.
The technical exploitation of this vulnerability requires an attacker to gain access to the administrative interface of the CMS, typically through valid user credentials or by exploiting additional authentication bypasses. Once inside the administrative editing interface, the attacker can craft malicious markdown content that contains embedded javascript payloads within the part_body_content parameter. The vulnerability stems from the CMS's failure to properly sanitize or encode user input before rendering it as part of the web page output. When other users navigate to pages containing this maliciously crafted content, their browsers execute the embedded javascript code within the context of their authenticated sessions. This creates a persistent threat that can be leveraged for session hijacking, credential theft, or redirection to malicious websites. The ATT&CK framework categorizes this as a code injection technique under T1190, specifically targeting web application vulnerabilities that allow for client-side code execution.
The operational impact of CVE-2018-5216 extends beyond simple data theft or defacement, as it provides attackers with persistent access to the administrative interface and potentially the entire content management system. This vulnerability enables attackers to modify or delete content, create new administrative users, or even escalate privileges within the CMS environment. The stored nature of the XSS payload means that the attack vector remains active until the malicious content is removed from the database, making it particularly dangerous for high-traffic websites where the vulnerability could affect numerous users over extended periods. Organizations using Radiant CMS 1.1.4 are particularly vulnerable because the default installation configuration does not include adequate input validation or output encoding for markdown content. The vulnerability also demonstrates poor defense-in-depth principles, as the CMS fails to implement proper content security policies or input validation at multiple layers of the application stack. Security teams should note that this vulnerability can be combined with other attacks such as session hijacking or privilege escalation to create more severe compromise scenarios.
Mitigation strategies for CVE-2018-5216 involve both immediate remediation and long-term architectural improvements. The most effective immediate solution is upgrading to a patched version of Radiant CMS that properly sanitizes markdown input and implements proper output encoding for all user-generated content. Organizations should also implement Content Security Policy headers to limit the execution of inline scripts and restrict external resource loading. Input validation should be strengthened to reject or sanitize any markdown syntax that could potentially lead to script execution. The implementation of proper output encoding mechanisms for all user-generated content, particularly within administrative interfaces, is crucial. Security teams should also consider implementing web application firewalls with rules specifically designed to detect and block XSS attempts. Regular security audits of web applications should include testing for similar input validation flaws, particularly in content management systems where user-generated content is processed through markdown parsers. The vulnerability highlights the importance of maintaining up-to-date software versions and implementing comprehensive input validation as fundamental security controls that align with NIST cybersecurity framework recommendations for protecting web applications from common attack vectors.