CVE-2026-81756 Overview
CVE-2026-81756 is an unauthenticated SQL injection vulnerability affecting the Smart Marketing SMS and Newsletters Forms plugin for WordPress in versions up to and including 5.1.24. The flaw allows remote attackers to inject arbitrary SQL statements into backend database queries without any authentication or user interaction. The issue is tracked under CWE-89 (Improper Neutralization of Special Elements used in an SQL Command). Public advisory information is available through the Patchstack SQL Injection Advisory.
Critical Impact
Unauthenticated attackers can extract sensitive data from the WordPress database and impact availability across affected sites.
Affected Products
- WordPress plugin: Smart Marketing SMS and Newsletters Forms
- Vulnerable versions: <= 5.1.24
- Deployments: WordPress sites using the smart-marketing-for-wp plugin
Discovery Timeline
- 2026-08-31 - CVE-2026-81756 published to NVD
- 2026-09-02 - Last updated in NVD database
Technical Details for CVE-2026-81756
Vulnerability Analysis
The Smart Marketing SMS and Newsletters Forms plugin fails to sanitize or parameterize user-supplied input before incorporating it into SQL queries. An unauthenticated attacker can craft HTTP requests that alter query logic executed by the WordPress backend database. Because the vulnerability is reachable without authentication, any internet-exposed WordPress instance running a vulnerable version is subject to exploitation. The scope change indicated by the CVSS vector reflects the attacker's ability to influence data beyond the immediate vulnerable component, including the wider WordPress database.
Root Cause
The root cause is improper neutralization of special elements used in an SQL command ([CWE-89]). Input arriving through plugin endpoints is concatenated directly into SQL statements rather than being passed through prepared statements or WordPress's $wpdb->prepare() API. This concatenation permits injection of SQL syntax that the database engine parses and executes.
Attack Vector
Attackers exploit the vulnerability over the network by sending crafted requests to plugin endpoints exposed by a vulnerable WordPress installation. No credentials, session, or user interaction are required. Successful exploitation can enable extraction of subscriber data, credentials, and other database contents, as well as denial-of-service conditions through resource-intensive queries. Refer to the Patchstack SQL Injection Advisory for further technical context.
Detection Methods for CVE-2026-81756
Indicators of Compromise
- Requests to Smart Marketing plugin endpoints containing SQL syntax such as UNION SELECT, SLEEP(, OR 1=1, or encoded variants.
- Unexpected outbound queries, error responses, or long response times originating from plugin request handlers.
- New or modified WordPress users, options, or plugin-related database rows without a corresponding admin action.
Detection Strategies
- Inspect web server and WordPress logs for POST or GET parameters targeting smart-marketing-for-wp routes that contain SQL metacharacters.
- Deploy WAF signatures for common SQL injection patterns and enable logging on plugin URIs.
- Correlate database error messages in PHP logs with inbound HTTP requests to identify probing activity.
Monitoring Recommendations
- Alert on repeated 500-level responses or timing anomalies on plugin endpoints.
- Monitor WordPress wp_users and wp_options tables for unauthorized changes.
- Track plugin inventory and version data across WordPress fleets to identify hosts running <= 5.1.24.
How to Mitigate CVE-2026-81756
Immediate Actions Required
- Identify all WordPress instances with the Smart Marketing SMS and Newsletters Forms plugin installed and confirm the version in use.
- Update the plugin to a fixed version once released by the vendor, per the Patchstack advisory.
- Rotate WordPress administrator credentials and database secrets if exploitation is suspected.
Patch Information
The advisory identifies versions <= 5.1.24 as vulnerable. Administrators should apply the vendor-supplied update once available and verify the installed version afterward. Consult the Patchstack SQL Injection Advisory for the current fixed-version guidance.
Workarounds
- Deactivate and remove the Smart Marketing SMS and Newsletters Forms plugin until a patched release is applied.
- Place a Web Application Firewall in front of the WordPress site with rules blocking SQL injection payloads on plugin URIs.
- Restrict access to plugin endpoints by IP allowlist where operationally feasible.
- Enforce least-privilege on the WordPress database user to limit the scope of a successful injection.
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
