CVE-2026-1807: InteractiveCalculator WordPress XSS Flaw

CVE-2026-1807 Overview

The InteractiveCalculator for WordPress plugin is vulnerable to Stored Cross-Site Scripting (XSS) via the plugin's interactivecalculator shortcode in all versions up to, and including, 1.0.3. The vulnerability stems from insufficient input sanitization and output escaping on user-supplied attributes, allowing authenticated attackers with contributor-level access and above to inject arbitrary web scripts into pages that execute whenever a user accesses the compromised page.

Critical Impact

Authenticated attackers can inject persistent malicious scripts that execute in the context of any user viewing the affected page, potentially leading to session hijacking, credential theft, or further site compromise.

Affected Products

• InteractiveCalculator for WordPress plugin versions up to and including 1.0.3

Discovery Timeline

• 2026-02-18 - CVE CVE-2026-1807 published to NVD
• 2026-02-18 - Last updated in NVD database

Technical Details for CVE-2026-1807

Vulnerability Analysis

This Stored Cross-Site Scripting vulnerability exists within the InteractiveCalculator WordPress plugin's shortcode implementation. When the plugin processes the interactivecalculator shortcode, it fails to properly sanitize and escape user-supplied attributes before rendering them in the HTML output. This allows attackers with at least contributor-level privileges to embed malicious JavaScript that persists in the database and executes when any user views the affected page.

The vulnerability is classified as CWE-79 (Improper Neutralization of Input During Web Page Generation), representing a classic stored XSS pattern where untrusted data is included in web pages without proper validation or escaping.

Root Cause

The root cause of this vulnerability lies in the shortcode handler function within interactivecalculator.php. The plugin accepts user-controlled attributes through the shortcode mechanism but does not apply proper input sanitization or output escaping before the attributes are rendered into the page HTML. WordPress provides functions like esc_attr(), esc_html(), and wp_kses() specifically for this purpose, but the vulnerable code fails to utilize these security mechanisms adequately.

Attack Vector

The attack vector is network-based and requires authenticated access at the contributor level or higher. An attacker with valid WordPress credentials can create or edit posts containing the vulnerable shortcode with malicious attribute values. The injected payload persists in the WordPress database and executes in the browser context of any visitor who views the affected page, including administrators.

The exploitation flow involves:

1. An attacker with contributor access creates a new post or edits an existing one
2. The attacker inserts the interactivecalculator shortcode with malicious JavaScript in one of its attributes
3. When any user (including administrators) views the published page, the malicious script executes in their browser session
4. The attacker can leverage this to steal session cookies, perform actions on behalf of the victim, or inject additional malicious content

For detailed technical information about the vulnerable code, see the WordPress Plugin Code Review.

Detection Methods for CVE-2026-1807

Indicators of Compromise

• Unusual JavaScript code within post content containing the interactivecalculator shortcode
• Posts or pages created by contributors containing script tags or event handlers in shortcode attributes
• Browser security console warnings about XSS or Content Security Policy violations on pages using the plugin
• Unexpected outbound network requests from client browsers when viewing calculator pages

Detection Strategies

• Review WordPress post content for suspicious patterns in interactivecalculator shortcode attributes
• Implement Content Security Policy (CSP) headers to detect and block inline script execution
• Monitor WordPress audit logs for posts containing potential XSS payloads created by non-admin users
• Deploy web application firewalls (WAF) with XSS detection rules to identify malicious shortcode submissions

Monitoring Recommendations

• Enable verbose logging for WordPress user activity, particularly post creation and editing events
• Configure browser-based XSS protection headers and monitor CSP violation reports
• Regularly audit posts and pages containing the interactivecalculator shortcode for suspicious content
• Monitor for anomalous administrator session activity that could indicate session hijacking

How to Mitigate CVE-2026-1807

Immediate Actions Required

• Update the InteractiveCalculator plugin to the latest patched version immediately
• Review all existing posts and pages containing the interactivecalculator shortcode for malicious content
• Audit contributor and author accounts for signs of compromise or unauthorized access
• Consider temporarily disabling the plugin until the update can be applied

Patch Information

The vulnerability has been addressed in plugin updates. Review the WordPress Plugin Changeset 3456849 and WordPress Plugin Changeset 3456870 for details on the security fixes. Additional information is available in the Wordfence Vulnerability Report.

Workarounds

• Deactivate the InteractiveCalculator plugin until a patched version can be installed
• Restrict contributor and author role capabilities using a role management plugin to prevent shortcode usage
• Implement strict Content Security Policy headers to mitigate script injection impacts
• Use a WordPress security plugin with XSS filtering capabilities to sanitize shortcode output

# Configuration example - Add CSP headers to wp-config.php or .htaccess
# Apache .htaccess example:
Header set Content-Security-Policy "default-src 'self'; script-src 'self'; style-src 'self' 'unsafe-inline';"

# Or in wp-config.php using PHP headers:
# header("Content-Security-Policy: default-src 'self'; script-src 'self';");