CVE-2016-8642 in Moodle
Summary
by MITRE
In Moodle 2.x and 3.x, the question engine allows access to files that should not be available.
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Analysis
by VulDB Data Team • 05/14/2026
The vulnerability identified as CVE-2016-8642 affects Moodle versions 2.x and 3.x, specifically targeting the question engine component that handles educational assessment functionality. This issue represents a critical access control flaw that undermines the security model of the learning management system. The question engine in Moodle is responsible for managing various question types, including those with embedded files, images, and other media elements that are integral to assessment delivery and grading processes. When users interact with questions containing file attachments, the system should enforce strict access controls to ensure that only authorized individuals can view or download specific resources.
The technical flaw manifests as improper file access validation within the question engine's file handling mechanisms. Attackers can exploit this vulnerability to bypass intended access restrictions and gain unauthorized access to files that should remain protected within the system's file hierarchy. This occurs because the question engine fails to properly validate user permissions when processing file requests, allowing malicious actors to construct specific URLs or API calls that circumvent the normal access control checks. The vulnerability is particularly concerning because it operates at the file system level, potentially exposing sensitive assessment materials, grading rubrics, or other confidential educational content that instructors and administrators intend to keep private.
The operational impact of this vulnerability extends beyond simple information disclosure, as it can lead to serious academic integrity issues and potential data breaches within educational institutions. An attacker who successfully exploits this vulnerability could access question bank files containing exam questions, answer keys, or grading criteria that should only be visible to authorized instructors or administrators. This access could enable malicious actors to compromise the integrity of assessments, potentially leading to grade manipulation, unauthorized access to exam content, or the extraction of proprietary educational materials. The vulnerability affects the core functionality of Moodle's assessment system, making it a high-risk issue for educational organizations that rely on the platform for their learning management needs.
Mitigation strategies for CVE-2016-8642 should focus on implementing proper access control validation within the question engine's file handling processes. Organizations should immediately upgrade to patched versions of Moodle 2.x and 3.x where the vulnerability has been addressed through proper file access validation mechanisms. System administrators should also implement additional monitoring of file access patterns and conduct regular security audits of question bank content. The vulnerability aligns with CWE-284, which addresses improper access control, and maps to ATT&CK technique T1078 for valid accounts and T1566 for credential access through exploitation of software vulnerabilities. Organizations should ensure that file access controls are properly enforced at multiple levels, including both application-level validation and proper file system permissions, to prevent unauthorized access to sensitive educational materials.