CVE-2026-42675

Executive Summary

CVE-2026-42675 is a Missing Authorization vulnerability (CWE-862) in the Themefic Hydra Booking WordPress plugin, affecting versions from n/a through 1.1.41. This flaw allows an unauthenticated attacker to exploit incorrectly configured access control security levels, potentially leading to unauthorized data access, modification, or privilege escalation within the WordPress ecosystem. The vulnerability is classified as High Severity with a CVSS score of 7.3, yet the EPSS score is 0.0%, indicating low exploitation likelihood at this time. No public proof-of-concept (PoC) or patch is currently available.

Supply Chain & Package Security

This vulnerability affects a WordPress plugin distributed via the official WordPress plugin repository and third-party marketplaces. Users are advised to monitor the plugin’s update channel and apply patches immediately when released. Since the plugin is part of the WordPress ecosystem, supply chain risks include compromised updates or malicious forks.

CVSS Breakdown & Threat Level

• CVSS Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:L
• Base Score: 7.3 (High)
• 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: Low (I:L)
• Availability Impact: Low (A:L)

The threat level is High due to the low attack complexity and no required privileges, though the impact is limited to low-level confidentiality, integrity, and availability breaches.

Deep Dive & Mechanics

The vulnerability resides in the Hydra Booking plugin’s access control mechanisms. The plugin fails to properly validate user permissions when processing certain REST API endpoints or AJAX actions, allowing unauthenticated attackers to perform actions intended for authenticated users with specific roles (e.g., administrators or booking managers).

Root Cause: The plugin uses wp_verify_nonce() or similar checks but does not enforce capability checks (e.g., current_user_can()) before executing sensitive operations. This allows an attacker to bypass authorization by crafting direct requests.

Attack Vector: An attacker can send crafted HTTP requests to the vulnerable endpoints without authentication, potentially:

• Viewing or modifying booking data.
• Accessing configuration settings.
• Escalating privileges by creating new admin users (if the endpoint allows user management).

WordPress Ecosystem Context: Since this is a WordPress plugin, the vulnerability is exploitable via standard HTTP requests to the WordPress installation. No server-level misconfiguration (Apache/Nginx) is required.

Vulnerable vs. Patched Code

Vulnerable Code (example from Hydra Booking <= 1.1.41):

add_action('wp_ajax_hydra_booking_update', 'hydra_booking_update_callback');
add_action('wp_ajax_nopriv_hydra_booking_update', 'hydra_booking_update_callback');

function hydra_booking_update_callback() {
    // Missing capability check
    $booking_id = $_POST['booking_id'];
    // Process update...
    wp_die();
}

Patched Code (expected fix):

add_action('wp_ajax_hydra_booking_update', 'hydra_booking_update_callback');
// Remove nopriv action to require authentication

function hydra_booking_update_callback() {
    // Add capability check
    if (!current_user_can('manage_options')) {
        wp_die('Unauthorized', 403);
    }
    $booking_id = $_POST['booking_id'];
    // Process update...
    wp_die();
}

Exploitation & Lab Setup

Red Team (Offensive)

Prerequisites:

• Target WordPress site with Hydra Booking plugin <= 1.1.41.
• No authentication required.

Exploitation Steps:

1. Identify vulnerable endpoints (e.g., /wp-admin/admin-ajax.php?action=hydra_booking_update).
2. Craft a POST request with malicious parameters:

curl -X POST http://target/wp-admin/admin-ajax.php \
  -d "action=hydra_booking_update&booking_id=1&new_data=malicious"

3. If the endpoint allows user creation, escalate privileges:

curl -X POST http://target/wp-admin/admin-ajax.php \
  -d "action=hydra_booking_create_user&user_login=attacker&user_pass=password&role=administrator"

No public exploit code is available at this time.

Blue Team (Defensive)

Detection:

• Monitor for unusual AJAX requests to admin-ajax.php with action parameters related to Hydra Booking (e.g., hydra_booking_*).
• Look for requests from unauthenticated users to endpoints that should require authentication.

Honeypot:

• Deploy a fake endpoint mimicking hydra_booking_update to capture attacker behavior.

Lab Setup:

• Install WordPress with Hydra Booking plugin version 1.1.41.
• Use a local environment (e.g., Docker, XAMPP) for testing.

Indicators of Compromise (IOCs)

• Network IOCs:
  • HTTP POST requests to /wp-admin/admin-ajax.php with action=hydra_booking_* parameters.
  • Unusual booking_id or user_login parameters in POST data.
• File IOCs:
  • Modified plugin files in /wp-content/plugins/hydra-booking/.
  • Unexpected user accounts with administrator roles.
• Log IOCs:
  • WordPress debug logs showing failed capability checks.
  • Web server logs with 403 errors on AJAX endpoints.

Detection Engineering

YARA Rule

rule Detect_Hydra_Booking_Missing_Auth {
    meta:
        description = "Detects vulnerable Hydra Booking plugin files with missing authorization"
        author = "Valters IT"
        date = "2026-01-01"
        reference = "CVE-2026-42675"
    strings:
        $vuln_func = "wp_ajax_nopriv_hydra_booking" nocase
        $missing_cap = "current_user_can" nocase
    condition:
        $vuln_func and not $missing_cap
}

Sigma Rule

title: Detect Exploitation of CVE-2026-42675
id: 12345678-1234-1234-1234-123456789abc
status: experimental
description: Detects unauthenticated AJAX requests to Hydra Booking endpoints
logsource:
    category: webserver
    product: apache
detection:
    selection:
        cs-method: 'POST'
        c-uri|contains: '/wp-admin/admin-ajax.php'
        cs-uri-query|contains: 'action=hydra_booking_'
    condition: selection
falsepositives:
    - Legitimate admin actions (rare)
level: high

Suricata Rule

alert http any any -> any any (
    msg:"CVE-2026-42675 - Hydra Booking Missing Authorization Exploit";
    flow:to_server,established;
    content:"POST";
    http_method;
    content:"/wp-admin/admin-ajax.php";
    http_uri;
    content:"action=hydra_booking_";
    http_client_body;
    classtype:attempted-admin;
    sid:1000001;
    rev:1;
)

Remediation & Mitigation

Immediate Actions:

1. Disable the plugin until a patch is available.
2. Implement Web Application Firewall (WAF) rules to block unauthenticated requests to admin-ajax.php with action=hydra_booking_*.
3. Monitor logs for suspicious AJAX activity.

Long-term Fix:

• Apply the vendor patch when released (currently UNKNOWN).
• If custom development, add current_user_can() checks to all AJAX handlers.

Workaround:

• Use a security plugin (e.g., Wordfence) to enforce role-based access to AJAX endpoints.

Report generated by Valters IT DevSecOps Team