CVE-2016-8869 in Joomla
Summary
by MITRE
The register method in the UsersModelRegistration class in controllers/user.php in the Users component in Joomla! before 3.6.4 allows remote attackers to gain privileges by leveraging incorrect use of unfiltered data when registering on a site.
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Analysis
by VulDB Data Team • 02/01/2025
The vulnerability identified as CVE-2016-8869 represents a critical privilege escalation flaw within the Joomla! content management system affecting versions prior to 3.6.4. This vulnerability exists within the Users component's controller logic specifically in the UsersModelRegistration class where the register method processes user registration requests. The flaw stems from inadequate input validation and sanitization practices that permit malicious actors to manipulate the registration process and potentially elevate their privileges during account creation. The vulnerability is classified under CWE-20 as a weakness involving improper input validation, specifically manifesting as improper sanitization of user-supplied data that should never be trusted in security-critical contexts.
The technical exploitation of this vulnerability occurs when an attacker crafts a malicious registration request that includes specially formatted data in the registration parameters. The flawed implementation fails to properly filter or validate the data passed through the registration method, allowing arbitrary privilege levels to be assigned to newly created user accounts. This misconfiguration enables attackers to register with elevated privileges, effectively bypassing the normal user registration restrictions that should prevent users from creating accounts with administrative or elevated permissions. The vulnerability operates at the application layer and can be exploited remotely without requiring any prior authentication or access to the system.
From an operational perspective, this vulnerability presents a severe risk to Joomla relies upon to maintain secure user access controls. The vulnerability aligns with ATT&CK technique T1078 which covers valid accounts and privilege escalation through legitimate access paths.
Mitigation strategies for CVE-2016-8869 focus on immediate patching of affected Joomla! installations to version 3.6.4 or later where the vulnerability has been addressed through proper input sanitization and validation. Organizations should also implement additional security controls including monitoring registration activities for unusual privilege assignments, implementing rate limiting on registration requests, and conducting regular security audits of user management components. Network-level protections such as web application firewalls can provide additional detection capabilities for suspicious registration patterns. The vulnerability highlights the importance of proper input validation practices and demonstrates how seemingly minor oversights in data handling can result in significant security breaches. Regular security assessments and adherence to secure coding practices should be maintained to prevent similar vulnerabilities in future implementations. System administrators should also consider implementing automated patch management processes to ensure timely deployment of security updates and reduce the window of exposure to known vulnerabilities.