CVE-2026-3657: My Sticky Bar WordPress SQLi Vulnerability

CVE-2026-3657 Overview

The My Sticky Bar plugin for WordPress contains a SQL injection vulnerability in the stickymenu_contact_lead_form AJAX action affecting all versions up to and including 2.8.6. This vulnerability arises from improper handling of user-controlled POST parameter names, which are directly used as SQL column identifiers in database INSERT operations. While the plugin applies esc_sql() and sanitize_text_field() sanitization to parameter values, it fails to validate or sanitize the parameter keys themselves, allowing attackers to inject malicious SQL through crafted parameter names.

Critical Impact
Unauthenticated attackers can exploit this vulnerability to perform blind time-based SQL injection attacks, enabling extraction of sensitive data from the WordPress database including user credentials, configuration data, and potentially personally identifiable information.

Affected Products

My Sticky Bar (mystickymenu) plugin for WordPress versions ≤ 2.8.6
WordPress installations using vulnerable plugin versions
Any site with the stickymenu_contact_lead_form AJAX endpoint accessible

Discovery Timeline

2026-03-12 - CVE CVE-2026-3657 published to NVD
2026-03-12 - Last updated in NVD database

Technical Details for CVE-2026-3657

Vulnerability Analysis

This SQL injection vulnerability (CWE-89) exploits a common oversight in WordPress plugin development where developers focus on sanitizing input values while neglecting the parameter names themselves. The vulnerable code path exists in the stickymenu_contact_lead_form AJAX handler within mystickymenu.php, specifically around lines 2386-2396 of version 2.8.6.

When processing contact form submissions, the plugin iterates through POST parameters and uses the parameter names directly as column identifiers in a call to $wpdb->insert(). This WordPress database abstraction method constructs an INSERT statement where the array keys become column names. Since these keys are not validated against a whitelist of expected columns or properly escaped for use as identifiers, an attacker can craft malicious parameter names containing SQL injection payloads.

The exploitation technique involves blind time-based data extraction. By injecting SQL commands like SLEEP() or conditional statements into the parameter names, attackers can infer database contents character by character based on response timing differences. This technique bypasses the value-level sanitization entirely since the injection occurs in the column identifier portion of the query.

Root Cause

The root cause is improper input validation where user-controlled POST parameter names are used directly as SQL column identifiers without sanitization or whitelist validation. While WordPress's $wpdb->insert() method prepares values safely, it does not escape or validate the column names passed to it. The plugin developers correctly sanitized parameter values using esc_sql() and sanitize_text_field(), but failed to apply any validation to the parameter keys that become column identifiers in the dynamically constructed SQL INSERT statement.

Attack Vector

The attack is network-accessible and requires no authentication or user interaction. An attacker can send specially crafted HTTP POST requests to the WordPress AJAX endpoint (/wp-admin/admin-ajax.php) with the action parameter set to stickymenu_contact_lead_form. By manipulating the names of additional POST parameters to include SQL injection payloads, the attacker can execute arbitrary SQL commands within the context of the INSERT statement.

The attack enables blind time-based data extraction, where attackers can systematically extract database contents including WordPress user tables, plugin configurations, and potentially sensitive customer data. The network attack vector combined with no required privileges makes this vulnerability particularly dangerous for publicly accessible WordPress installations.

For technical implementation details, refer to the WordPress StickyMenu PHP Code and the Wordfence Vulnerability Report.

Detection Methods for CVE-2026-3657

Indicators of Compromise

Unusual POST requests to /wp-admin/admin-ajax.php with action=stickymenu_contact_lead_form containing malformed or suspicious parameter names
Database query logs showing INSERT statements with unexpected column names or SQL syntax within column identifiers
Abnormally slow response times on AJAX endpoints indicating time-based blind SQL injection attempts
Web server logs containing encoded SQL keywords in POST parameter names (e.g., SLEEP, BENCHMARK, IF, CASE)

Detection Strategies

Implement Web Application Firewall (WAF) rules to inspect POST parameter names for SQL injection patterns, not just values
Monitor database slow query logs for INSERT operations with unusual timing patterns or syntax errors
Deploy endpoint detection solutions capable of identifying time-based SQL injection attack patterns through response latency analysis
Review access logs for repeated requests to the vulnerable AJAX action from single IP addresses with varying parameter structures

Monitoring Recommendations

Enable detailed query logging on WordPress database connections to capture full INSERT statements including column names
Configure alerting for HTTP 500 errors or database errors originating from the My Sticky Bar plugin files
Implement real-time monitoring for AJAX requests with anomalous parameter structures or encoded characters in field names
Monitor for data exfiltration indicators such as DNS queries or outbound connections following suspicious AJAX activity

How to Mitigate CVE-2026-3657

Immediate Actions Required

Update the My Sticky Bar plugin to version 2.8.7 or later immediately
If immediate patching is not possible, temporarily disable the My Sticky Bar plugin until the update can be applied
Review database logs for evidence of exploitation attempts and investigate any suspicious activity
Consider implementing a WAF rule to block requests to the vulnerable AJAX action as a temporary measure

Patch Information

The vulnerability has been addressed in My Sticky Bar version 2.8.7. Site administrators should update through the WordPress plugin update mechanism or by downloading the patched version from the WordPress plugin repository. The specific changes can be reviewed in the version changeset.

Workarounds

Disable the My Sticky Bar plugin entirely if the update cannot be applied immediately
Implement WAF rules to block POST requests containing SQL keywords or special characters in parameter names targeting the affected AJAX action
Restrict access to /wp-admin/admin-ajax.php for unauthenticated users if the contact form functionality is not required for public users
Use a security plugin to add additional input validation layers for AJAX requests

bash

# Example .htaccess rule to temporarily block the vulnerable AJAX action
# Add to WordPress root .htaccess file as emergency mitigation
<IfModule mod_rewrite.c>
RewriteEngine On
RewriteCond %{REQUEST_URI} ^/wp-admin/admin-ajax\.php$ [NC]
RewriteCond %{QUERY_STRING} action=stickymenu_contact_lead_form [NC,OR]
RewriteCond %{REQUEST_METHOD} POST
RewriteCond %{REQUEST_BODY} stickymenu_contact_lead_form
RewriteRule .* - [F,L]
</IfModule>