WooCommerce Ajax Product Filter Plugin Vulnerable to SQL Injection (CVE-2026-3396)

The WooCommerce Ajax Product Filter (WCAPF) plugin, a WordPress extension, is susceptible to a time-based SQL Injection vulnerability (CVE-2026-3396). This flaw stems from inadequate input sanitization of the post-author parameter and insufficient preparation within the existing SQL query structure. Specifically, all versions of the plugin up to and including version 4.2.3 are affected. An unauthenticated attacker can exploit this vulnerability by injecting malicious SQL code into the post-author parameter. Successful exploitation allows the attacker to manipulate database queries and extract sensitive information without requiring authentication. This vulnerability poses a significant risk to e-commerce sites using the WCAPF plugin, as attackers could potentially access customer data, administrative credentials, or other confidential information.

Attack Chain

1. An unauthenticated attacker identifies a WooCommerce website using a vulnerable version (<=4.2.3) of the WCAPF plugin.
2. The attacker crafts a malicious HTTP request targeting an endpoint that utilizes the vulnerable post-author parameter.
3. The crafted request includes SQL injection payload within the post-author parameter, designed to extract data using time-based techniques. For example, the attacker might use a SLEEP() function to introduce delays based on conditional database queries.
4. The web server processes the request and passes the unsanitized post-author parameter to the database query.
5. The injected SQL code manipulates the original query, causing the database to execute the attacker’s malicious commands.
6. Based on the response time (due to the SLEEP() function), the attacker infers whether their injected SQL query was successful in retrieving specific data.
7. The attacker iteratively refines their SQL injection payload to extract sensitive information, such as user credentials or customer details.
8. The attacker exfiltrates the obtained data, potentially using it for identity theft, financial fraud, or further attacks against the compromised website.

Impact

Successful exploitation of CVE-2026-3396 can lead to the complete compromise of the vulnerable WooCommerce website’s database. An attacker could potentially access sensitive customer data, including names, addresses, credit card details, and purchase history. Furthermore, administrative credentials could be stolen, allowing the attacker to gain full control over the website. This can result in significant financial losses, reputational damage, and legal liabilities for the affected e-commerce business. While the exact number of affected websites is unknown, any online store using the WCAPF plugin versions 4.2.3 or earlier is potentially at risk.

Recommendation

• Upgrade the WCAPF plugin to a version greater than 4.2.3 to patch CVE-2026-3396 (references: CVE-2026-3396).
• Deploy the Sigma rule Detect WooCommerce SQL Injection Attempt to identify potential exploitation attempts in web server logs (references: Sigma rule).
• Implement input validation and sanitization on the post-author parameter to prevent SQL injection attacks (references: Attack Chain).
• Monitor web server logs for suspicious requests containing SQL injection payloads, particularly those targeting WCAPF plugin endpoints (references: Sigma rule, Attack Chain).