CVE-2017-20257: SQL Injection in Joomla! Quiz Deluxe 3.7.4 – Unauthenticated Data Extraction

Technical summary

The vulnerability exists in the ajaxaction.flag_question task of Quiz Deluxe 3.7.4, where user-supplied input in the stu_quiz_id and flag_quest parameters is not properly sanitized before being used in SQL queries. This classic SQL injection (CWE-89) allows unauthenticated attackers to inject arbitrary SQL syntax, bypass authentication logic, enumerate database contents, or extract confidential data. The attack surface is the HTTP interface; no special network conditions are required.

Business impact

An attacker exploiting this vulnerability could extract quiz data, user accounts, email addresses, password hashes, or any other information stored in the Joomla! database. For organizations using Quiz Deluxe for training, assessments, or credential verification, compromise could expose sensitive intellectual property, employee performance records, or customer data. Reputational damage and regulatory fines under GDPR or similar frameworks are realistic outcomes if personally identifiable information is breached.

Affected systems

Joomla! installations running the Quiz Deluxe component version 3.7.4 are directly affected. The component is a third-party extension typically installed manually, so exposure depends on adoption within an organization's Joomla! estate. Verify which Joomla! sites have Quiz Deluxe installed and specifically identify those running version 3.7.4 or earlier. Joomla! core versions are not inherently affected unless the Quiz Deluxe component is present.

Exploitability

This vulnerability is highly exploitable. No authentication is required, the attack can be carried out over the network without special tools, and the injection points (stu_quiz_id and flag_quest parameters) are straightforward to identify and manipulate. A proof-of-concept could be constructed by an attacker with basic SQL knowledge in hours. The barrier to exploitation is low, making it likely to be weaponized rapidly if widely discovered.

Remediation

Immediately update Quiz Deluxe to a patched version released by the vendor. Verify against the Quiz Deluxe vendor advisory for the specific patch version that addresses CVE-2017-20257. If an update is not yet available, disable the Quiz Deluxe component entirely or restrict access to it via firewall rules or IP whitelisting. Review database access logs and query logs for evidence of exploitation or data exfiltration.

Patch guidance

Contact the Quiz Deluxe vendor or check the official component repository for a security update released after June 2026. Apply the patch to all Joomla! installations running affected versions. Test the patch in a staging environment to confirm compatibility with your Joomla! version and any customizations before deploying to production. After patching, clear Joomla! cache to ensure the updated component is loaded.

Detection guidance

Monitor HTTP access logs for requests to the ajaxaction.flag_question task with unusual or encoded parameters (stu_quiz_id and flag_quest). Look for SQL keywords such as UNION, SELECT, OR, SCRIPT, or quote characters (single or double) in parameter values. Implement Web Application Firewall (WAF) rules to block or alert on SQL injection patterns targeting the Quiz Deluxe component. Query database audit logs for unexpected SELECT statements on user or quiz tables, especially from the Joomla! application user. Check for recent administrative user accounts created during the vulnerability window.

Why prioritize this

This vulnerability scores 8.2 (HIGH) because it allows unauthenticated remote attackers to exfiltrate sensitive data with minimal effort and no user interaction. Confidentiality is fully compromised; data integrity is partially compromised. While service availability is not directly impacted, the ease of exploitation and the critical nature of database access make this a top-tier priority for organizations running Quiz Deluxe.

Risk score, explained

The CVSS 3.1 score of 8.2 reflects Network attack vector (AV:N), Low attack complexity (AC:L), no privilege requirement (PR:N), no user interaction (UI:N), and Unchanged scope (S:U). High confidentiality impact (C:H) accounts for data extraction; Limited integrity impact (I:L) for potential data modification; No availability impact (A:N) as the service continues running. This HIGH severity rating aligns with real-world exploitation likelihood and business damage potential.

Frequently asked questions