CVE-2025-13835: Arconix Shortcodes Stored XSS Vulnerability

CVE-2025-13835 Overview

CVE-2025-13835 is a Stored Cross-Site Scripting (XSS) vulnerability affecting the Arconix Shortcodes plugin for WordPress, developed by Tyche Softwares. This vulnerability (CWE-79) allows attackers with authenticated access to inject malicious scripts into web pages that are persistently stored and executed when other users view the affected content.

The vulnerability has been assigned a CVSS 3.1 score of 6.5 (Medium severity) with the vector string CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:L. This indicates a network-based attack vector with low attack complexity, requiring low privileges and user interaction. The changed scope means the vulnerability can affect resources beyond the vulnerable component.

Critical Impact

Authenticated attackers can inject persistent malicious scripts that execute in the browsers of site visitors and administrators, potentially leading to session hijacking, credential theft, and website defacement.

Affected Products

• Arconix Shortcodes plugin versions from n/a through 2.1.19
• WordPress installations utilizing the vulnerable Arconix Shortcodes plugin
• Websites with authenticated users who have shortcode creation privileges

Discovery Timeline

• 2025-12-01 - CVE-2025-13835 published to NVD
• 2025-12-02 - Last updated in NVD database

Technical Details for CVE-2025-13835

Vulnerability Analysis

The Arconix Shortcodes plugin for WordPress fails to properly neutralize user-supplied input during web page generation, resulting in a Stored Cross-Site Scripting (XSS) vulnerability. When authenticated users create or modify shortcode content, the plugin does not adequately sanitize or escape malicious input before storing it in the database and rendering it on the front-end.

Stored XSS vulnerabilities are particularly dangerous because the malicious payload persists on the server and is delivered to every user who views the affected page. Unlike reflected XSS, which requires victims to click on a malicious link, stored XSS attacks execute automatically when legitimate pages are loaded.

The EPSS (Exploit Prediction Scoring System) probability for this vulnerability is 0.034% with a percentile ranking of 9.388, indicating a relatively low likelihood of exploitation in the wild at this time.

Root Cause

The root cause of this vulnerability lies in improper input validation and output encoding within the Arconix Shortcodes plugin. Specifically, user-controllable input processed through the shortcode functionality is not properly sanitized before being stored in the WordPress database, and is not adequately escaped when rendered in HTML output. This allows attackers to inject arbitrary JavaScript code that will execute in the context of the victim's browser session.

Attack Vector

The attack vector for CVE-2025-13835 is network-based and requires low-privileged authentication. An attacker with at least contributor-level access to a WordPress site can exploit this vulnerability by crafting malicious shortcode content containing JavaScript payloads. When other users, including administrators, view pages or posts containing the malicious shortcode, the injected script executes in their browser context.

The exploitation typically involves injecting event handlers or script tags within shortcode attributes that bypass the plugin's insufficient sanitization mechanisms. The malicious payload is stored in the WordPress database and persists until manually removed, creating a persistent attack that can affect multiple victims over time.

Detection Methods for CVE-2025-13835

Indicators of Compromise

• Unusual JavaScript code present in shortcode content within the WordPress database
• Unexpected <script> tags or event handlers (e.g., onerror, onload, onclick) in post content
• Reports of browser alerts, redirects, or unusual behavior when viewing specific pages
• Suspicious network requests originating from the website to unknown external domains
• Unexpected changes to user sessions or administrative access patterns

Detection Strategies

Security teams should implement the following detection strategies:

1. Database Content Scanning: Regularly scan the wp_posts and wp_postmeta tables for suspicious JavaScript patterns, encoded payloads, and malicious HTML attributes associated with shortcode content.

2. Web Application Firewall (WAF) Rules: Deploy WAF rules to detect and block common XSS patterns in POST requests to WordPress admin endpoints, particularly those handling shortcode creation and modification.

3. Content Security Policy (CSP) Monitoring: Implement strict CSP headers and monitor for policy violations that may indicate XSS exploitation attempts.

4. User Activity Logging: Enable comprehensive logging of content creation and modification activities, particularly for users with contributor or higher privileges.

Monitoring Recommendations

Organizations should establish continuous monitoring for this vulnerability by:

• Implementing real-time alerting for suspicious shortcode content patterns
• Monitoring plugin versions across all WordPress installations and flagging instances running Arconix Shortcodes version 2.1.19 or earlier
• Reviewing access logs for unusual patterns of content modification followed by page views from different IP addresses
• Utilizing WordPress security plugins that provide XSS detection capabilities

How to Mitigate CVE-2025-13835

Immediate Actions Required

• Update the Arconix Shortcodes plugin to a version newer than 2.1.19 when a patched version becomes available
• Review existing shortcode content for any malicious JavaScript or HTML injections
• Audit user accounts with contributor-level access or higher for suspicious activity
• Implement additional input validation and output encoding at the theme or WAF level
• Consider temporarily disabling the Arconix Shortcodes plugin if an immediate update is not available

Patch Information

Consult the official Patchstack advisory for detailed patch information: Patchstack Vulnerability Database

Monitor Tyche Softwares' official channels and the WordPress plugin repository for security updates addressing this vulnerability. When a patched version is released, test the update in a staging environment before deploying to production.

Workarounds

If an immediate patch is not available, implement the following workarounds to reduce risk:

1. Restrict User Privileges: Limit contributor and author roles to trusted users only, as the vulnerability requires authenticated access.

2. Content Security Policy: Implement strict CSP headers to mitigate the impact of any successful XSS exploitation by restricting script execution sources.

3. Web Application Firewall: Deploy WAF rules to filter common XSS payloads in shortcode parameters.

4. Plugin Deactivation: If the functionality is not critical, consider temporarily deactivating the Arconix Shortcodes plugin until a security update is available.

5. Manual Input Sanitization: Add custom sanitization filters for shortcode output in your theme's functions.php file as a temporary measure.