CVE-2025-31071

Executive Summary

CVE-2025-31071 is a Missing Authorization vulnerability in the HotStar – Multi-Purpose Business Theme by Themeton, a WordPress theme. This flaw allows an unauthenticated attacker to exploit incorrectly configured access control security levels, potentially leading to unauthorized access to sensitive data or functionality. The vulnerability affects all versions up to and including 1.4. With a CVSS score of 5.3 (Medium), the risk is elevated due to the low attack complexity and network-based vector, though the impact is limited to confidentiality. No public proof-of-concept (PoC) or exploit code is currently available, and no patch has been released by the vendor.

Supply Chain & Package Security

This vulnerability resides in a WordPress theme distributed via the official WordPress theme repository and third-party marketplaces. As a WordPress ecosystem issue, it affects sites using the HotStar theme. No NPM, PyPI, Go, or Ruby packages are involved. The risk is primarily to site owners who have installed this theme without additional security hardening.

CVSS Breakdown & Threat Level

• CVSS Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N
• Base Score: 5.3 (Medium)
• Attack Vector: Network (AV:N)
• Attack Complexity: Low (AC:L)
• Privileges Required: None (PR:N)
• User Interaction: None (UI:N)
• Scope: Unchanged (S:U)
• Confidentiality Impact: Low (C:L)
• Integrity Impact: None (I:N)
• Availability Impact: None (A:N)

Threat Level: Medium. The vulnerability is easy to exploit remotely without authentication, but the impact is limited to low-level information disclosure. However, in a WordPress context, this could expose sensitive configuration data or user information.

Deep Dive & Mechanics

The vulnerability stems from a Missing Authorization check (CWE-862) in the HotStar theme's AJAX handlers or REST API endpoints. The theme likely registers custom WordPress AJAX actions or REST routes that are intended for authenticated users (e.g., theme settings, demo import, or data export) but fails to verify the user's capabilities before processing requests.

Root Cause: The theme's code does not implement current_user_can() or wp_verify_nonce() checks on certain functions, allowing unauthenticated attackers to trigger them via crafted HTTP requests.

Attack Vector: An attacker sends a specially crafted HTTP request to the WordPress site (e.g., POST /wp-admin/admin-ajax.php?action=hotstar_export_data) without any authentication token. The theme processes the request and returns sensitive data.

Impact: Unauthorized access to theme configuration, user data, or internal site information. This could lead to further attacks if combined with other vulnerabilities.

Vulnerable vs. Patched Code

Since no patch is available, the vulnerable code is presumed to be in the theme's functions.php or custom plugin files. A typical vulnerable pattern:

Vulnerable Code (functions.php):

add_action('wp_ajax_nopriv_hotstar_export', 'hotstar_export_data');
function hotstar_export_data() {
    // No capability check
    $data = get_option('hotstar_settings');
    wp_send_json($data);
}

Patched Code (hypothetical):

add_action('wp_ajax_nopriv_hotstar_export', 'hotstar_export_data');
function hotstar_export_data() {
    if (!current_user_can('manage_options')) {
        wp_die('Unauthorized', 403);
    }
    $data = get_option('hotstar_settings');
    wp_send_json($data);
}

The patched version adds a capability check (manage_options) to ensure only administrators can access the data.

Exploitation & Lab Setup

Red Team (Exploitation)

Prerequisites:

• A WordPress site running HotStar theme <= 1.4.
• Network access to the site.

Exploitation Steps:

1. Identify vulnerable AJAX actions by analyzing the theme's JavaScript or source code (e.g., hotstar_export, hotstar_import).
2. Send a crafted request:

   curl -X POST https://target-site.com/wp-admin/admin-ajax.php \
     -d "action=hotstar_export" \
     -H "Content-Type: application/x-www-form-urlencoded"
   

3. If successful, the response contains sensitive data (e.g., theme settings, API keys).

No public exploit code is available. The above is a generic example based on the vulnerability type.

Blue Team (Detection & Hardening)

Detection:

• Monitor for unusual AJAX requests to admin-ajax.php with unknown or suspicious actions.
• Look for requests without a valid nonce or authentication cookie.

Hardening:

• Disable the theme until a patch is released.
• Implement a Web Application Firewall (WAF) rule to block requests to unknown AJAX actions.
• Use a security plugin (e.g., Wordfence) to monitor for unauthorized access attempts.

Indicators of Compromise (IOCs)

• Network IOCs:
  • HTTP POST requests to /wp-admin/admin-ajax.php with action=hotstar_* parameters.
  • Requests lacking a valid X-WP-Nonce header or authentication cookie.
• File IOCs:
  • Modified functions.php or theme files with missing capability checks.
• Log IOCs:
  • WordPress debug log entries showing wp_ajax_nopriv_* actions triggered by unauthenticated users.

Detection Engineering

YARA Rule

rule Detect_HotStar_Missing_Auth {
    meta:
        description = "Detects missing authorization in HotStar theme functions.php"
        author = "Valters IT"
        date = "2025-04-10"
        cve = "CVE-2025-31071"
    strings:
        $ajax_action = /add_action\s*\(\s*['\"]wp_ajax_nopriv_hotstar_/
        $no_cap = !/current_user_can/
    condition:
        $ajax_action and $no_cap
}

Sigma Rule

title: HotStar Theme Missing Authorization Exploitation
id: 8a9b7c6d-5e4f-3a2b-1c0d-9e8f7a6b5c4d
status: experimental
description: Detects exploitation attempts of CVE-2025-31071 via AJAX requests
author: Valters IT
logsource:
    category: webserver
    product: apache
    service: access_combined
detection:
    selection:
        cs-method: 'POST'
        cs-uri-query|contains: 'admin-ajax.php'
        cs-uri-query|contains: 'action=hotstar_'
    condition: selection
falsepositives:
    - Legitimate theme functionality (if patched)
level: high

Suricata Rule

alert http $HOME_NET any -> $EXTERNAL_NET any (
    msg:"CVE-2025-31071 HotStar Theme Missing Authorization Attempt";
    flow:to_server,established;
    content:"POST"; http_method;
    content:"admin-ajax.php"; http_uri;
    content:"action=hotstar_"; http_client_body;
    classtype:attempted-recon;
    sid:10000001;
    rev:1;
)

Remediation & Mitigation

Immediate Actions:

1. Disable the HotStar theme and switch to a default WordPress theme (e.g., Twenty Twenty-Four) until a patch is released.
2. Implement a WAF rule to block requests to admin-ajax.php with action=hotstar_* parameters from unauthenticated users.
3. Monitor logs for suspicious AJAX activity.

Long-term Fix:

• Contact the vendor (Themeton) for a security update.
• If no patch is forthcoming, consider replacing the theme with a secure alternative.
• Apply the principle of least privilege to all WordPress AJAX handlers.

Valters IT Signature: This report was generated by Valters IT Cyber Threat Intelligence Division. For questions, contact cti@valters-it.com.