CVE-2026-6391 Overview
The Sentence To SEO (keywords, description and tags) plugin for WordPress contains a Cross-Site Request Forgery (CSRF) vulnerability affecting all versions up to and including 1.0. The flaw stems from missing or incorrect nonce validation in the create_admin_page() function. Unauthenticated attackers can inject malicious web scripts and modify plugin settings by tricking a site administrator into clicking a crafted link. Successful exploitation requires user interaction but no authentication on the attacker side. The issue is tracked as CWE-352: Cross-Site Request Forgery.
Critical Impact
An attacker who lures a logged-in WordPress administrator to a malicious page can silently update Sentence To SEO plugin settings and inject scripts that execute in the administrator's browser context.
Affected Products
- WordPress plugin: Sentence To SEO (keywords, description and tags)
- All versions up to and including 1.0
- WordPress sites where the plugin is installed and active
Discovery Timeline
- 2026-05-20 - CVE-2026-6391 published to NVD
- 2026-05-20 - Last updated in NVD database
Technical Details for CVE-2026-6391
Vulnerability Analysis
The vulnerability resides in the plugin's administrative settings handler. The create_admin_page() function processes incoming form submissions to update plugin configuration but does not verify a WordPress nonce token. Without nonce validation, WordPress cannot confirm that a state-changing request originated from a legitimate administrator session.
Because the handler also fails to sanitize the submitted setting values, an attacker can supply payloads containing HTML or JavaScript. Those payloads are stored in plugin options and later rendered, producing a stored Cross-Site Scripting (XSS) condition chained to the CSRF entry point. The combined defect impacts confidentiality and integrity of administrative session data and site configuration.
References to the vulnerable code locations are published in the WordPress Plugin Code Review and the Wordfence Vulnerability Report.
Root Cause
The root cause is the absence of wp_verify_nonce() or check_admin_referer() calls in the settings save path. WordPress requires nonce validation on any privileged action to bind the request to an authenticated session. Skipping this check allows any cross-origin form post to update plugin options when an administrator is logged in.
Attack Vector
An attacker hosts a malicious page or sends a crafted link to a WordPress administrator. When the administrator visits the page while authenticated, the browser auto-submits a POST request to the plugin's settings endpoint carrying attacker-controlled values. The server accepts the request because the session cookie is valid and no nonce is enforced. The injected payload persists in plugin settings and executes in any administrator browser that subsequently loads the affected page.
No verified exploit code is publicly available. See the Wordfence advisory
and the linked WordPress plugin source code references for technical details
on the vulnerable create_admin_page() function in index.php.
Detection Methods for CVE-2026-6391
Indicators of Compromise
- Unexpected modifications to Sentence To SEO plugin settings, including SEO keywords, descriptions, or tag fields containing HTML or JavaScript markup.
- Outbound POST requests to /wp-admin/admin.php or the plugin's settings endpoint with no matching Referer header from the same site.
- Administrator session activity originating from external referrers immediately preceding settings changes.
- New <script>, <iframe>, or event-handler attributes appearing in rendered SEO meta tags on public pages.
Detection Strategies
- Audit the wp_options table for plugin option entries containing HTML tags, JavaScript, or encoded payloads.
- Review WordPress audit logs for update_option calls targeting Sentence To SEO settings without a corresponding admin UI navigation event.
- Inspect web server access logs for POST requests to the plugin settings handler that lack the expected _wpnonce parameter.
Monitoring Recommendations
- Enable a WordPress activity logging plugin to capture option changes with user, IP, and referrer metadata.
- Configure web application firewall (WAF) rules to flag cross-origin POST requests to wp-admin endpoints.
- Monitor public page source for injected scripts in meta description and keyword tags.
How to Mitigate CVE-2026-6391
Immediate Actions Required
- Deactivate and remove the Sentence To SEO plugin until a patched version is published by the vendor.
- Review the plugin's stored options and remove any values containing HTML or JavaScript payloads.
- Force a password reset and session invalidation for all WordPress administrator accounts that may have visited untrusted links.
- Apply a WAF rule to block cross-site POST requests to the plugin's admin endpoint.
Patch Information
No vendor patch is referenced in the NVD entry at the time of publication. Administrators should monitor the WordPress plugin repository and the Wordfence Vulnerability Report for an updated release that adds nonce validation and input sanitization to create_admin_page().
Workarounds
- Uninstall the plugin until an updated version with nonce validation is released.
- Restrict /wp-admin/ access by IP allowlist at the web server or WAF layer.
- Require administrators to use separate browser profiles or sessions for WordPress administration to limit CSRF exposure.
- Deploy a security plugin that enforces nonce checks and Content Security Policy (CSP) headers on admin pages.
# Disable the plugin via WP-CLI until a fix is available
wp plugin deactivate sentence-to-seo
wp plugin delete sentence-to-seo
# Audit plugin options for injected content
wp option list --search='sentence*' --format=table
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
