CVE-2026-13701 Overview
CVE-2026-13701 is a Stored Cross-Site Scripting (XSS) vulnerability in the Advanced Excerpt WordPress plugin versions before 4.5. The plugin fails to sanitize and escape one of its settings before rendering it on the front end of the site. An authenticated administrator can inject malicious JavaScript that executes in the browser of any visitor viewing affected pages. The flaw is significant on WordPress multisite installations, where administrators normally lack the unfiltered_html capability and are therefore expected to be restricted from injecting raw HTML or scripts. The issue is tracked under CWE-79.
Critical Impact
An authenticated administrator can store JavaScript in plugin settings that executes in every visitor's browser, enabling session theft, defacement, and drive-by redirection.
Affected Products
- Advanced Excerpt WordPress plugin versions prior to 4.5
- WordPress single-site installations using the plugin
- WordPress multisite networks where site administrators lack unfiltered_html
Discovery Timeline
- 2026-08-10 - CVE-2026-13701 published to NVD
- 2026-08-10 - Last updated in NVD database
Technical Details for CVE-2026-13701
Vulnerability Analysis
The Advanced Excerpt plugin exposes configurable settings that control how post excerpts are rendered on the front end. One of these settings is written back into page output without proper sanitization on input and without escaping on output. An administrator who saves crafted content into the vulnerable setting causes that content to be stored in the WordPress options table and later emitted verbatim inside HTML rendered to every site visitor.
On a standard single-site WordPress install, administrators already hold the unfiltered_html capability, so this class of finding is lower value in that context. The impact increases on WordPress multisite, where the unfiltered_html capability is stripped from site administrators by design. This vulnerability grants a multisite administrator a script-execution primitive that the WordPress capability model is meant to deny.
Successful exploitation runs attacker JavaScript in the origin of the target site under the victim visitor's session. Attackers can hijack authenticated sessions, exfiltrate cookies and CSRF tokens, pivot to privileged actions on behalf of logged-in users, or redirect visitors to malicious infrastructure.
Root Cause
The root cause is missing input sanitization when the plugin saves its setting value and missing output escaping (for example, esc_html, esc_attr, or wp_kses) when the value is echoed into the rendered page. This is a textbook Improper Neutralization of Input During Web Page Generation weakness (CWE-79).
Attack Vector
Exploitation requires an authenticated user with administrator-level access to the plugin's settings page and requires a visitor to load a page that renders the tainted excerpt configuration. The stored payload persists across sessions until the setting is cleared or the plugin is updated. No user interaction beyond viewing a page is required from the victim visitor.
See the WPScan Vulnerability Report for the technical write-up.
Detection Methods for CVE-2026-13701
Indicators of Compromise
- Unexpected <script> tags, on* event handlers, or javascript: URIs stored in the Advanced Excerpt plugin settings within the WordPress wp_options table.
- Outbound requests from visitor browsers to unfamiliar domains sourced from pages that render post excerpts.
- Recent settings changes to the Advanced Excerpt plugin by administrator accounts that do not normally manage plugin configuration.
Detection Strategies
- Query the wp_options table for Advanced Excerpt option rows and inspect stored values for HTML or script content.
- Run authenticated web application scans against pages that render excerpts to identify reflected script execution.
- Review the WordPress audit log for update_option events targeting the plugin's settings, correlated with the administrator account that made the change.
Monitoring Recommendations
- Alert on new outbound domains contacted by browsers on pages served from the WordPress host.
- Monitor for anomalous administrator logins, especially on multisite networks where site admins should not hold unfiltered_html.
- Track plugin version inventory and flag any host still running Advanced Excerpt below version 4.5.
How to Mitigate CVE-2026-13701
Immediate Actions Required
- Update the Advanced Excerpt plugin to version 4.5 or later on every WordPress site in the environment.
- Audit the plugin's stored settings and remove any HTML, JavaScript, or event-handler content injected before patching.
- Rotate credentials and force re-authentication for administrator and editor accounts on affected sites.
Patch Information
Upgrade to Advanced Excerpt version 4.5 or later, which introduces the missing sanitization and output escaping. Refer to the WPScan Vulnerability Report for advisory details and fixed-version confirmation.
Workarounds
- Deactivate and remove the Advanced Excerpt plugin until the patched version can be deployed.
- Restrict administrator access on multisite networks and review which accounts can modify plugin settings.
- Deploy a web application firewall rule to block requests containing script payloads sent to the plugin's settings endpoints.
# Inspect Advanced Excerpt plugin settings for injected script content
wp option list --search='advanced_excerpt*' --format=table
# Update the plugin to the fixed version across a multisite network
wp plugin update advanced-excerpt --version=4.5 --network
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
