A subtle but critical security flaw recently placed over 40,000 WordPress websites in jeopardy, stemming from a popular tool designed for engagement and data collection. The Quiz and Survey Master (QSM) plugin, widely used for creating interactive content, was found to contain a significant SQL injection vulnerability. This issue, officially designated as CVE-2025-67987, affected all versions up to and including 10.3.1. What made this particular threat so concerning was its accessibility; the vulnerability could be exploited by authenticated users with privileges as low as a standard Subscriber. This meant that a vast number of user accounts, often considered low-risk, suddenly became potential entry points for attackers seeking to manipulate database queries and gain unauthorized access to sensitive information. The incident serves as a stark reminder that even the most trusted components of a website’s ecosystem can harbor hidden dangers, highlighting the continuous need for vigilance and prompt security updates for all site administrators. The widespread nature of the plugin meant the potential impact was considerable, threatening the integrity of data across a diverse range of websites.
Anatomy of the SQL Injection Flaw
The vulnerability’s origin lay deep within the plugin’s code, specifically in a REST API function responsible for retrieving data related to quiz questions. The core of the problem was a fundamental failure in input validation. A specific request parameter, identified as is_linking, was processed by the system with an implicit trust that it would always be a simple numeric value. This parameter was then inserted directly into a raw SQL statement without undergoing any sanitization or being handled through a secure prepared statement. This oversight created a classic SQL injection vector. Because the system did not use prepared statements, which separate the SQL command logic from the data being inserted, an attacker could submit a specially crafted string in the is_linking parameter. This malicious input could contain additional SQL commands, which the database would then execute as if they were part of the original, intended query. This allowed a low-privilege user to effectively hijack the database’s operations, potentially leading to the theft of user data, quiz results, or other confidential information stored on the website, or even manipulation of the database itself.
Resolution and Key Security Takeaways
The path to remediation began following a responsible disclosure process initiated on November 21, 2025, by security researcher Doan Dinh Van, a member of the Patchstack Alliance. Upon being notified, the developers of the Quiz and Survey Master plugin acted to address the critical issue. On December 4, 2025, they released version 10.3.2, which contained the necessary patch to neutralize the threat. The fix itself was direct and effective: the developers implemented proper input sanitization by forcing the vulnerable is_linking parameter to be an integer using the intval function. This simple change ensured that any non-numeric or malicious characters would be stripped away, rendering the injection attack impossible. This incident provided a crucial lesson on the fundamentals of secure web application development. It underscored the absolute necessity of treating all user-supplied input as untrustworthy until it has been rigorously validated and sanitized. Furthermore, it reinforced the industry-standard best practice of exclusively employing prepared statements for all database interactions to prevent the execution of unintended SQL code, a defensive measure that could have prevented this vulnerability entirely.
