CVE-2026-59537: Sender Newsletter Plugin SQLi Vulnerability

CVE-2026-59537 Overview

CVE-2026-59537 is a SQL injection vulnerability in the Sender – Newsletter, SMS and Email Marketing Automation for WooCommerce plugin for WordPress. The flaw affects versions up to and including 2.10.22. An authenticated administrator can inject arbitrary SQL statements into database queries processed by the plugin. The issue is classified under CWE-89 (Improper Neutralization of Special Elements used in an SQL Command).

The vulnerability requires high privileges, but successful exploitation causes a scope change and allows attackers to read sensitive database contents and impact application availability.

Critical Impact
An authenticated administrator can execute arbitrary SQL against the WordPress database, exposing subscriber data, marketing lists, and other sensitive tables managed by the plugin.

Affected Products

Sender – Newsletter, SMS and Email Marketing Automation for WooCommerce plugin versions <= 2.10.22
WordPress deployments with the affected plugin installed
WooCommerce sites relying on the plugin for marketing automation

Discovery Timeline

2026-07-27 - CVE-2026-59537 published to NVD
2026-07-27 - Last updated in NVD database

Technical Details for CVE-2026-59537

Vulnerability Analysis

The vulnerability resides in database query handling within the Sender plugin. Input supplied through an administrator-accessible interface reaches SQL statements without proper parameterization or escaping. This allows the attacker to break out of the intended query context and append arbitrary SQL clauses.

Because the affected code path runs with database privileges granted to the WordPress user, injected statements execute against all tables the plugin can reach. The scope change indicated in the vulnerability metadata reflects that impact extends beyond the plugin's own data to the broader WordPress database.

The requirement for administrator privileges reduces opportunistic exploitation. However, administrator credentials are frequently phished or reused, and multi-admin WordPress installations expand the population of accounts capable of triggering the flaw.

Root Cause

The root cause is missing input neutralization in SQL query construction, consistent with CWE-89. Attacker-controlled values are concatenated into SQL statements rather than being passed through prepared statements or $wpdb->prepare().

Attack Vector

Exploitation is performed over the network against the WordPress administrative interface. An authenticated administrator submits crafted parameters to a vulnerable plugin endpoint. The injected SQL executes when the plugin queries the database, returning data or modifying execution flow as directed by the attacker.

No public proof-of-concept, exploit code, or CISA KEV entry currently references CVE-2026-59537. See the Patchstack Vulnerability Advisory for the vendor-verified technical write-up.

Detection Methods for CVE-2026-59537

Indicators of Compromise

Unexpected SQL syntax fragments such as UNION SELECT, SLEEP(, information_schema, or comment sequences (--, /*) in HTTP request parameters targeting /wp-admin/ endpoints associated with the Sender plugin.
Anomalous administrator sessions issuing repeated requests to plugin-specific admin-ajax or settings routes.
Sudden spikes in database CPU or query duration correlated with plugin request activity.

Detection Strategies

Enable WordPress and web server request logging, and alert on plugin admin routes receiving parameters containing SQL metacharacters.
Deploy a Web Application Firewall (WAF) with SQL injection signatures in front of /wp-admin/.
Review MySQL general or slow query logs for statements that reference plugin tables but contain concatenated or malformed clauses.

Monitoring Recommendations

Baseline administrator activity and alert on off-hours logins or new admin accounts.
Monitor plugin file integrity and WordPress core tables for unauthorized modifications.
Forward WordPress, WAF, and database logs to a centralized analytics platform for correlated queries against plugin endpoints.

How to Mitigate CVE-2026-59537

Immediate Actions Required

Update the Sender – Newsletter, SMS and Email Marketing Automation for WooCommerce plugin to a version later than 2.10.22 once released by the vendor.
Audit all administrator accounts and remove or downgrade unused privileged users.
Enforce multi-factor authentication on every WordPress administrator account.
Rotate credentials and API keys stored by the plugin if compromise is suspected.

Patch Information

Refer to the Patchstack Vulnerability Advisory for the current patched version and vendor guidance. Apply the fixed release through the WordPress plugin updater or manual replacement.

Workarounds

Disable the Sender plugin until a patched version is installed if the marketing functionality is not required.
Restrict access to /wp-admin/ by source IP through the web server or upstream firewall.
Deploy WAF rules that block SQL injection patterns on plugin-specific admin endpoints.

bash

# Example nginx restriction limiting wp-admin access to a trusted network
location ^~ /wp-admin/ {
    allow 203.0.113.0/24;
    deny all;
    try_files $uri $uri/ /index.php?$args;
}