CVE-2026-28562: Wpforo Forum SQL Injection Vulnerability

CVE-2026-28562 Overview

CVE-2026-28562 is an unauthenticated SQL injection vulnerability affecting wpForo version 2.4.14, a popular WordPress forum plugin developed by Gvectors. The vulnerability exists in the Topics::get_topics() function where the ORDER BY clause relies on ineffective esc_sql() sanitization on unquoted identifiers. Attackers can exploit the wpfob parameter with CASE WHEN payloads to perform blind boolean extraction of credentials from the WordPress database.

This vulnerability allows remote attackers to extract sensitive information including user credentials without any authentication, posing a significant risk to WordPress sites running the vulnerable plugin version.

Critical Impact

Unauthenticated attackers can extract WordPress user credentials and other sensitive database contents through blind SQL injection techniques.

Affected Products

• gvectors wpforo_forum version 2.4.14
• WordPress installations with wpForo Forum plugin

Discovery Timeline

• 2026-02-28 - CVE-2026-28562 published to NVD
• 2026-03-05 - Last updated in NVD database

Technical Details for CVE-2026-28562

Vulnerability Analysis

This SQL injection vulnerability (CWE-89) stems from improper input validation in the wpForo plugin's topic handling functionality. The Topics::get_topics() function processes user-supplied input through the wpfob parameter to control the ORDER BY clause of SQL queries. While the plugin attempts to sanitize this input using WordPress's esc_sql() function, this protection is insufficient for unquoted identifiers in ORDER BY clauses.

The esc_sql() function is designed to escape strings for use within quoted contexts in SQL queries. However, when applied to ORDER BY parameters that are not enclosed in quotes, attackers can inject malicious SQL code that bypasses this sanitization entirely. This allows for blind boolean-based SQL injection attacks where attackers can systematically extract data by observing differences in application responses.

Root Cause

The root cause of this vulnerability is the misapplication of the esc_sql() sanitization function to an unquoted SQL identifier. WordPress's esc_sql() function escapes quotes and special characters, but these escape mechanisms have no effect when the sanitized value is placed directly into the query without surrounding quotes. The ORDER BY clause typically accepts column names without quotes, creating a scenario where the sanitization provides a false sense of security while leaving the application vulnerable.

Proper mitigation requires either strict whitelist validation of allowed column names or the use of parameterized queries with proper binding for dynamic ORDER BY columns.

Attack Vector

The vulnerability is exploited via network-accessible HTTP requests to the WordPress site. Attackers target the wpfob parameter with specially crafted payloads containing CASE WHEN constructs. These conditional expressions allow attackers to infer database contents through blind boolean extraction techniques.

In a typical attack scenario, the attacker sends requests with payloads that cause different ordering behavior based on conditional checks against database values. By iterating through possible character values and observing response patterns, attackers can systematically extract sensitive data such as usernames, password hashes, and email addresses from the WordPress database.

The attack requires no authentication, making it accessible to any remote attacker who can reach the vulnerable WordPress installation. For additional technical details, see the VulnCheck Advisory.

Detection Methods for CVE-2026-28562

Indicators of Compromise

• Unusual or malformed values in the wpfob HTTP parameter containing SQL keywords such as CASE, WHEN, THEN, or SELECT
• High volume of requests to wpForo topic listing endpoints with varying parameter values
• Sequential or automated request patterns indicative of blind SQL injection enumeration
• Error logs showing SQL syntax errors or unusual query behavior related to ORDER BY clauses

Detection Strategies

• Implement Web Application Firewall (WAF) rules to detect SQL injection patterns in the wpfob parameter
• Monitor WordPress access logs for requests containing SQL injection signatures targeting wpForo endpoints
• Deploy SentinelOne Singularity XDR to detect anomalous behavior patterns associated with database extraction attacks
• Enable WordPress database query logging and alert on queries with unexpected ORDER BY syntax

Monitoring Recommendations

• Configure real-time alerting for SQL injection attempt patterns in web server logs
• Monitor database connection patterns for unusual query volumes that may indicate data extraction
• Implement rate limiting on forum topic listing endpoints to slow enumeration attacks
• Review and audit wpForo plugin logs for suspicious parameter manipulation attempts

How to Mitigate CVE-2026-28562

Immediate Actions Required

• Update wpForo plugin to the latest patched version immediately
• Implement WAF rules to block requests containing SQL injection patterns in the wpfob parameter
• Review WordPress user accounts for signs of compromise and force password resets if necessary
• Audit database access logs for evidence of successful exploitation

Patch Information

Administrators should update the wpForo plugin to a version that addresses this SQL injection vulnerability. Check the WordPress Plugin Directory for the latest version and update instructions. Review the wpForo Developer Documentation for any security-related release notes.

Workarounds

• Implement strict input validation at the web server or WAF level to reject requests with SQL injection patterns
• Temporarily disable or restrict access to forum topic listing functionality until patched
• Use a security plugin that provides SQL injection protection for WordPress
• Consider placing the WordPress admin and database on a network segment with additional access controls

# Example .htaccess rule to block SQL injection attempts in wpfob parameter
RewriteEngine On
RewriteCond %{QUERY_STRING} wpfob=.*(\(|case|when|select|union) [NC]
RewriteRule ^.* - [F,L]