CVE-2016-9837 in Joomla
Summary
by MITRE
An issue was discovered in templates/beez3/html/com_content/article/default.php in Joomla! before 3.6.5. Inadequate permissions checks in the Beez3 layout override of the com_content article view allow users to view articles that should not be publicly accessible, as demonstrated by an index.php?option=com_content&view=article&id=1&template=beez3 request.
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Analysis
by VulDB Data Team • 10/12/2022
The vulnerability identified as CVE-2016-9837 represents a critical access control flaw within the Joomla! content management system affecting versions prior to 3.6.5. This issue specifically targets the Beez3 template's layout override implementation for the com_content component, creating a pathway for unauthorized users to access restricted content. The flaw manifests through inadequate permission validation mechanisms within the template override file located at templates/beez3/html/com_content/article/default.php, which fails to properly verify user privileges before rendering article content. The vulnerability is particularly concerning because it operates at the presentation layer, where the template override logic does not properly enforce the same access controls that are typically applied at the component level, allowing attackers to bypass content restriction policies through a simple URL parameter manipulation.
The technical exploitation of this vulnerability occurs through a straightforward GET request pattern that leverages the template parameter to trigger the vulnerable code path. When a user accesses an article with the template parameter set to beez3, the system processes the request through the compromised template override file instead of the standard component logic. This deviation from normal processing flow means that the access control checks that would normally be enforced by the com_content component are effectively bypassed or circumvented. The flaw resides in the template override architecture where the Beez3 template's default.php file fails to properly integrate with Joomla!'s access control mechanisms, creating a scenario where content visibility is determined by the template selection rather than by proper user authorization checks. This represents a classic case of insufficient input validation and access control enforcement, which aligns with CWE-285 access control vulnerabilities.
The operational impact of this vulnerability extends beyond simple information disclosure, as it enables unauthorized access to sensitive content that administrators intended to keep private or restricted to specific user groups. Attackers can exploit this weakness to view articles that are marked as private, registered only, or assigned to specific user levels, effectively undermining the entire user permissions system within Joomla's access control features to protect confidential information, as this flaw provides a direct method for bypassing those protections without requiring elevated privileges or complex attack vectors. The vulnerability also demonstrates how template overrides can introduce security gaps when not properly validated against the core access control policies.
Mitigation strategies for CVE-2016-9837 focus primarily on updating to Joomla's access control mechanisms. Organizations should also establish security review processes for custom template development that include access control validation as part of the standard development lifecycle. This vulnerability highlights the importance of maintaining security awareness throughout the entire Joomla! ecosystem, including template customization and override practices, and aligns with ATT&CK technique T1068 for bypassing security controls through application-level vulnerabilities.