CVE-2025-12192

Executive Summary

CVE-2025-12192 is a medium-severity information disclosure vulnerability affecting The Events Calendar plugin for WordPress, up to and including version 6.15.9. The vulnerability resides in the /wp-json/the-events-calendar/v1/sysinfo REST API endpoint. Due to a loose comparison (==) in PHP when validating the API key, an unauthenticated attacker can send a boolean value (e.g., true) as the key parameter. If the site administrator has enabled the "Yes, automatically share my system information with The Events Calendar support team" setting, the attacker can retrieve the full system report, which includes sensitive server and WordPress configuration details. This information can be used to plan further attacks. No patch is currently available.

WordPress Ecosystem Context

This vulnerability is specific to the WordPress plugin ecosystem. The flaw is in the plugin's REST API endpoint and does not involve the core WordPress or server software (Apache/Nginx). The attack vector is entirely within the WordPress application layer.

CVSS Breakdown & Threat Level

• CVSS Score: 5.3 (Medium)
• Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N
• Attack Vector (AV): Network – The vulnerability is exploitable remotely.
• Attack Complexity (AC): Low – No special conditions are required.
• Privileges Required (PR): None – No authentication is needed.
• User Interaction (UI): None – The victim does not need to perform any action.
• Scope (S): Unchanged – The exploit cannot affect other components.
• Confidentiality (C): Low – Only system information is disclosed, not user data.
• Integrity (I): None – No data can be modified.
• Availability (A): None – No denial of service.

Threat Level: Medium. While the direct impact is limited to information disclosure, the leaked data (e.g., PHP version, active plugins, server paths) can significantly aid an attacker in exploiting other vulnerabilities.

Deep Dive & Mechanics

The vulnerability is caused by a PHP loose comparison (==) in the plugin's REST API authentication logic. The endpoint /wp-json/the-events-calendar/v1/sysinfo is designed to return a system report only if a valid opt-in key is provided. This key is stored in the WordPress options table when the administrator enables the "automatically share" setting.

The flawed code compares the provided key to the stored key using == instead of ===. In PHP, == performs type juggling. When a boolean value like true is compared to a string, PHP converts the string to a boolean. Any non-empty string (including the stored key) evaluates to true. Therefore, sending true as the key bypasses the check.

Attack Flow:

1. The attacker sends a GET request to /wp-json/the-events-calendar/v1/sysinfo?key=true.
2. The plugin retrieves the stored opt-in key from the database.
3. The comparison $provided_key == $stored_key is executed.
4. PHP converts $stored_key (a non-empty string) to boolean true.
5. The comparison true == true passes.
6. The plugin returns the full system report in JSON format.

Vulnerable vs. Patched Code

Vulnerable Code (<= 6.15.9):

// In the REST API callback
$stored_key = get_option('tec_sysinfo_optin_key');
$provided_key = $_GET['key'];

if ($provided_key == $stored_key) {
    // Return system info
    return rest_ensure_response($sysinfo);
}

Patched Code (Hypothetical):

// In the REST API callback
$stored_key = get_option('tec_sysinfo_optin_key');
$provided_key = $_GET['key'];

if (is_string($provided_key) && hash_equals($stored_key, $provided_key)) {
    // Return system info
    return rest_ensure_response($sysinfo);
}

The patched version uses hash_equals() for timing-safe comparison and explicitly checks that the provided key is a string, preventing type juggling.

Exploitation & Lab Setup

Red Team (Exploitation)

Prerequisites:

• A WordPress site with The Events Calendar plugin version <= 6.15.9.
• The "Yes, automatically share my system information" setting must be enabled in the plugin's settings.

Exploit Steps:

1. Identify the target WordPress site.
2. Send a GET request to the vulnerable endpoint with a boolean key:

   curl -X GET "https://target.com/wp-json/the-events-calendar/v1/sysinfo?key=true"
   

3. If the setting is enabled, the response will contain the full system report in JSON format.

Example Response (truncated):

{
  "wordpress_version": "6.4.2",
  "php_version": "8.1.0",
  "active_plugins": ["the-events-calendar/the-events-calendar.php", "akismet/akismet.php"],
  "server_software": "Apache/2.4.57 (Ubuntu)",
  "wp_debug": false,
  "memory_limit": "256M"
}

Blue Team (Detection & Prevention)

Detection:

• Monitor REST API access logs for requests to /wp-json/the-events-calendar/v1/sysinfo with unusual query parameters (e.g., key=true, key=false, key=1).
• Look for repeated requests from the same IP address to this endpoint.

Prevention:

• Disable the "automatically share" setting in the plugin's admin panel.
• Implement a Web Application Firewall (WAF) rule to block requests to /wp-json/the-events-calendar/v1/sysinfo from unauthenticated users.
• Apply the vendor patch as soon as it becomes available.

Indicators of Compromise (IOCs)

• Network IOCs:
  • HTTP GET requests to /wp-json/the-events-calendar/v1/sysinfo with key=true, key=false, or key=1.
  • Unusual User-Agent strings in such requests (e.g., curl/7.68.0).
• File IOCs:
  • No files are created or modified by this exploit.
• Log IOCs:
  • Web server access logs showing 200 responses to the vulnerable endpoint from unauthenticated IPs.

Detection Engineering

YARA Rule

rule Detect_CVE_2025_12192_Exploit {
    meta:
        description = "Detects HTTP requests exploiting CVE-2025-12192 in The Events Calendar plugin"
        author = "Valters IT"
        date = "2025-02-20"
        reference = "https://nvd.nist.gov/vuln/detail/CVE-2025-12192"
    strings:
        $endpoint = "/wp-json/the-events-calendar/v1/sysinfo"
        $key_param = "key=true" nocase
        $key_param2 = "key=false" nocase
        $key_param3 = "key=1" nocase
    condition:
        any of ($endpoint) and any of ($key_param*)
}

Sigma Rule

title: CVE-2025-12192 Exploitation Attempt
id: 8a3f7c2e-5d1b-4a9f-8c6e-2b3d1f0a7e9c
status: experimental
description: Detects attempts to exploit the information disclosure vulnerability in The Events Calendar plugin
author: Valters IT
date: 2025/02/20
logsource:
    category: webserver
    product: apache
    service: access
detection:
    selection:
        cs-method: 'GET'
        cs-uri-query|contains: '/wp-json/the-events-calendar/v1/sysinfo'
        cs-uri-query|contains|any:
            - 'key=true'
            - 'key=false'
            - 'key=1'
    condition: selection
falsepositives:
    - Legitimate plugin functionality (rare)
level: high

Suricata Rule

alert http any any -> any any (msg:"CVE-2025-12192 - The Events Calendar Sysinfo Disclosure Attempt"; flow:to_server,established; content:"GET"; http_method; content:"/wp-json/the-events-calendar/v1/sysinfo"; http_uri; content:"key=true"; http_uri; classtype:attempted-recon; sid:1000001; rev:1;)

Remediation & Mitigation

Immediate Actions:

1. Disable the "automatically share" setting: Navigate to The Events Calendar settings and uncheck the option "Yes, automatically share my system information with The Events Calendar support team."
2. Block the endpoint: Use a WAF or .htaccess rule to deny access to /wp-json/the-events-calendar/v1/sysinfo for unauthenticated users.

   <IfModule mod_rewrite.c>
   RewriteEngine On
   RewriteCond %{REQUEST_URI} ^/wp-json/the-events-calendar/v1/sysinfo [NC]
   RewriteCond %{HTTP_COOKIE} !wordpress_logged_in [NC]
   RewriteRule .* - [F,L]
   </IfModule>
   

3. Monitor logs: Review web server logs for any exploitation attempts.

Long-Term Fix:

• Apply the vendor patch as soon as it is released. The fix should replace the loose comparison with a strict comparison using hash_equals().

Workaround:

• If the plugin is not essential, consider deactivating it until a patch is available.

Valters IT
Securing Digital Frontiers