CVE-2025-53275

Executive Summary

CVE-2025-53275 is a DOM-Based Cross-Site Scripting (XSS) vulnerability identified in the Leyka WordPress plugin, developed by VaultDweller. This flaw allows an attacker to inject malicious scripts into a web page's Document Object Model (DOM) via user-supplied input that is improperly neutralized. The vulnerability affects all versions of Leyka up to and including 3.32.1. As a WordPress plugin, this issue is specific to the WordPress ecosystem and does not involve server-level components like Apache or Nginx.

The CVSS score of 6.5 (Medium) reflects the need for user interaction and the potential for partial compromise of confidentiality, integrity, and availability. The EPSS score of 0.0% indicates a very low probability of exploitation in the wild at this time, but the lack of a patch makes this a significant risk for sites using the plugin.

Supply Chain & Package Security

This vulnerability resides in a WordPress plugin distributed through the official WordPress plugin repository. Users who installed Leyka via the WordPress admin dashboard or directly from the repository are affected. The plugin is not distributed via NPM, PyPI, Go, or Ruby ecosystems, but the supply chain risk is still present due to the plugin's direct integration into WordPress sites. Administrators should monitor the plugin's update channel for a patched version.

CVSS Breakdown & Threat Level

• Attack Vector (AV): Network (N) – The vulnerability can be exploited remotely.
• Attack Complexity (AC): Low (L) – No special conditions are required.
• Privileges Required (PR): None (N) – No authentication is needed.
• User Interaction (UI): Required (R) – The victim must click a crafted link or visit a malicious page.
• Scope (S): Changed (C) – The impact extends beyond the vulnerable component.
• Confidentiality (C): Low (L) – Limited data exposure.
• Integrity (I): Low (L) – Limited data modification.
• Availability (A): Low (L) – Limited service disruption.

Threat Level: Medium. While the CVSS score is 6.5, the lack of a patch and the plugin's widespread use in charitable donation sites elevate the risk. DOM-based XSS can be used to steal session cookies, deface pages, or redirect users to phishing sites.

Deep Dive & Mechanics

The vulnerability stems from improper neutralization of user input during web page generation. In the Leyka plugin, certain JavaScript functions process user-controlled data (e.g., donation amounts, campaign parameters) and insert it into the DOM without proper sanitization. An attacker can craft a URL or input containing malicious JavaScript that, when processed by the plugin's client-side code, executes in the victim's browser.

For example, a donation form might accept a amount parameter that is reflected in a success message. If the plugin uses innerHTML or document.write without escaping, an attacker could inject <script>alert('XSS')</script>.

The attack flow:

1. Attacker crafts a malicious link: https://victim-site.com/?leyka_amount=<script>malicious_code</script>
2. Victim clicks the link.
3. The Leyka plugin's JavaScript reads the leyka_amount parameter and inserts it into the DOM.
4. The browser executes the injected script, leading to XSS.

Vulnerable vs. Patched Code

Since no patch is available, the vulnerable code pattern is described below. A patched version would sanitize input using textContent or a DOMPurify library.

Vulnerable Code (JavaScript):

// leyka.js (vulnerable)
function displayDonationMessage() {
    var amount = getParameterByName('leyka_amount');
    document.getElementById('donation-message').innerHTML = 'Thank you for donating ' + amount + '!';
}

Patched Code (Hypothetical):

// leyka.js (patched)
function displayDonationMessage() {
    var amount = getParameterByName('leyka_amount');
    var sanitizedAmount = DOMPurify.sanitize(amount);
    document.getElementById('donation-message').textContent = 'Thank you for donating ' + sanitizedAmount + '!';
}

Exploitation & Lab Setup

Red Team (Offensive)

Lab Setup:

1. Install WordPress with Leyka plugin version 3.32.1.
2. Create a donation page with the vulnerable parameter.

Exploit Payload:

https://victim-site.com/donate/?leyka_amount=<img src=x onerror=alert(document.cookie)>

Steps:

1. Craft the malicious URL with the XSS payload.
2. Send the link to the victim via phishing email or social engineering.
3. When the victim clicks, the script executes, stealing cookies or performing actions on their behalf.

Blue Team (Defensive)

Detection:

• Monitor web logs for suspicious query parameters containing <script>, <img onerror>, or other HTML/JavaScript constructs.
• Use WAF rules to block common XSS patterns.

Mitigation:

• Disable the Leyka plugin until a patch is released.
• Implement Content Security Policy (CSP) headers to restrict script execution.
• Use a Web Application Firewall (WAF) with XSS detection rules.

Indicators of Compromise (IOCs)

• URL Patterns: ?leyka_amount=<script>, ?leyka_amount=<img, ?leyka_amount=javascript:
• Network Traffic: Outbound connections to attacker-controlled domains from the victim's browser.
• Log Entries: HTTP requests with leyka_amount parameter containing encoded or raw HTML/JavaScript.
• File Hashes: (None available for this CVE)

Detection Engineering

YARA Rule

rule CVE_2025_53275_DOM_XSS {
    meta:
        description = "Detects DOM-based XSS attempts targeting Leyka plugin"
        author = "Valters IT"
        date = "2025-04-10"
        reference = "CVE-2025-53275"
    strings:
        $xss1 = "leyka_amount=" nocase
        $xss2 = "<script" nocase
        $xss3 = "onerror=" nocase
        $xss4 = "onload=" nocase
    condition:
        any of ($xss*) and #xss1 > 0
}

Sigma Rule

title: CVE-2025-53275 DOM-Based XSS in Leyka Plugin
id: 7a8b9c0d-1e2f-3a4b-5c6d-7e8f9a0b1c2d
status: experimental
description: Detects HTTP requests with suspicious leyka_amount parameter
author: Valters IT
date: 2025-04-10
logsource:
    category: webserver
    product: apache
detection:
    selection:
        c-uri|contains: "leyka_amount="
        c-uri|contains|any:
            - "<script"
            - "onerror="
            - "onload="
            - "javascript:"
    condition: selection
falsepositives:
    - Legitimate use of donation amounts with special characters (rare)
level: high

Suricata Rule

alert http any any -> any any (msg:"CVE-2025-53275 DOM-Based XSS in Leyka Plugin"; flow:to_server,established; content:"leyka_amount="; http_uri; pcre:"/(<script|onerror=|onload=|javascript:)/i"; sid:1000001; rev:1;)

Remediation & Mitigation

1. Immediate Action: Disable the Leyka plugin on all WordPress sites until a patched version is released.
2. Workaround: If disabling is not possible, implement a Web Application Firewall (WAF) rule to block requests containing leyka_amount with HTML/JavaScript content.
3. Code Fix: The vendor should update the plugin to sanitize all user inputs using textContent or a library like DOMPurify before inserting into the DOM.
4. Monitoring: Enable logging for all HTTP requests and monitor for suspicious patterns.
5. User Education: Advise users not to click on unsolicited links containing donation parameters.

Valters IT
Securing Digital Frontiers