CVE-2026-1651: Email Subscribers WordPress SQLi Vulnerability

CVE-2026-1651 Overview

The Email Subscribers by Icegram Express plugin for WordPress is vulnerable to SQL Injection via the workflow_ids parameter in all versions up to, and including, 5.9.16. The vulnerability stems from insufficient escaping on the user-supplied parameter and lack of sufficient preparation on the existing SQL query. This makes it possible for authenticated attackers, with administrator-level access and above, to append additional SQL queries into already existing queries that can be used to extract sensitive information from the database.

Critical Impact

Authenticated attackers with administrator privileges can exploit this SQL Injection vulnerability to extract sensitive data from the WordPress database, potentially compromising user credentials, personal information, and site configuration data.

Affected Products

• Email Subscribers by Icegram Express plugin for WordPress versions up to and including 5.9.16
• WordPress installations using vulnerable versions of the Icegram Express plugin
• Sites with administrator-level users who could be compromised or act maliciously

Discovery Timeline

• 2026-03-04 - CVE-2026-1651 published to NVD
• 2026-03-04 - Last updated in NVD database

Technical Details for CVE-2026-1651

Vulnerability Analysis

This SQL Injection vulnerability (CWE-89) affects the Email Subscribers by Icegram Express plugin for WordPress. The flaw exists in the workflow management functionality, specifically in the class-es-db-workflows.php file at line 379. The vulnerability allows authenticated users with administrator-level privileges to manipulate SQL queries through the workflow_ids parameter.

The vulnerability requires network access and high privileges (administrator-level) to exploit. While the privilege requirement limits the attack surface, compromised administrator accounts or insider threats could leverage this vulnerability to extract highly sensitive information including user data, email subscriber lists, and potentially other database contents.

Root Cause

The root cause of this vulnerability is insufficient input sanitization and improper use of prepared statements in the SQL query handling. The workflow_ids parameter is passed to the database query without adequate escaping or parameterization, allowing attackers to inject malicious SQL code that gets executed alongside the legitimate query.

The vulnerable code path exists in the workflow database class, where user-supplied input is incorporated into SQL queries without proper sanitization. This violates secure coding practices that mandate the use of prepared statements with parameterized queries to prevent SQL injection attacks.

Attack Vector

The attack is executed over the network and requires the attacker to have authenticated access with administrator-level privileges. The exploitation process involves:

1. An attacker with administrator credentials accesses the Email Subscribers plugin interface
2. The attacker crafts a malicious request containing SQL injection payloads in the workflow_ids parameter
3. The unsanitized input is incorporated into the database query
4. The injected SQL code executes, allowing the attacker to extract data or manipulate database contents

For detailed technical analysis and code examples, see the GitHub Gist Code Snippet and the WordPress Plugin Source File.

Detection Methods for CVE-2026-1651

Indicators of Compromise

• Unusual database queries originating from the Email Subscribers plugin, particularly involving the workflow_ids parameter
• Database error logs showing SQL syntax errors or unexpected query structures
• Audit logs revealing administrator accounts accessing workflow functionality with abnormal parameters
• Evidence of data exfiltration or unauthorized database access patterns

Detection Strategies

• Monitor web application firewall (WAF) logs for SQL injection patterns targeting WordPress plugin endpoints
• Implement database activity monitoring to detect anomalous queries from the Email Subscribers plugin
• Review WordPress admin activity logs for suspicious workflow-related operations
• Deploy intrusion detection rules targeting common SQL injection payloads in HTTP parameters

Monitoring Recommendations

• Enable detailed logging for database queries and monitor for UNION-based or time-based blind SQL injection patterns
• Configure alerts for administrator actions within the Email Subscribers plugin interface
• Implement real-time monitoring of database query execution times to detect exploitation attempts
• Regularly audit administrator account access and investigate any anomalous login patterns

How to Mitigate CVE-2026-1651

Immediate Actions Required

• Update the Email Subscribers by Icegram Express plugin to version 5.9.17 or later immediately
• Audit administrator accounts for any signs of compromise or unauthorized access
• Review database logs for evidence of prior exploitation attempts
• Consider temporarily disabling the plugin if immediate patching is not possible

Patch Information

A security fix has been released by the plugin developers. The WordPress Plugin Changeset contains the security patch addressing this vulnerability. Users should update to the latest version of the Email Subscribers by Icegram Express plugin, which implements proper input sanitization and prepared statements for the affected query.

For additional vulnerability details, refer to the Wordfence Vulnerability Report.

Workarounds

• Restrict administrator account access to only essential personnel until patching is complete
• Implement web application firewall rules to block SQL injection attempts targeting the workflow_ids parameter
• Enable additional authentication factors for WordPress administrator accounts
• Monitor and log all activity from administrator accounts with access to the Email Subscribers plugin

# Configuration example - WAF rule to block SQL injection in workflow_ids parameter
# Add to .htaccess or server configuration
RewriteEngine On
RewriteCond %{QUERY_STRING} workflow_ids=.*(\%27|\'|union|select|insert|drop|update|delete) [NC]
RewriteRule .* - [F,L]