CVE-2025-22697

Executive Summary

CVE-2025-22697 is a reflected Cross-Site Scripting (XSS) vulnerability in the WordPress plugin Responsive Blocks (responsive-block-editor-addons) by CyberChimps, affecting versions from n/a through 1.9.9. This flaw allows an attacker to inject arbitrary JavaScript into a web page via a crafted request, which is then reflected back to the victim's browser. The vulnerability is classified as Improper Neutralization of Input During Web Page Generation (CWE-79). With a CVSS score of 6.5 (Medium), it requires user interaction but no authentication, making it a significant risk for WordPress sites using this plugin. No public exploit code or patch details are currently available, and the EPSS score is 0.0%, indicating low exploitation activity at this time.

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 CyberChimps. Since no patch is available, the plugin remains a supply chain risk for any site using it.

CVSS Breakdown & Threat Level

• CVSS Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:L
• Base Score: 6.5 (Medium)
• Attack Vector: Network (AV:N) – Exploitable remotely.
• Attack Complexity: Low (AC:L) – No special conditions required.
• Privileges Required: None (PR:N) – No authentication needed.
• User Interaction: Required (UI:R) – Victim must click a crafted link.
• Scope: Changed (S:C) – Impact may extend beyond the vulnerable component.
• Confidentiality Impact: Low (C:L) – Limited data exposure.
• Integrity Impact: Low (I:L) – Limited modification of content.
• Availability Impact: Low (A:L) – Limited disruption.

Threat Level: Medium. While the CVSS score is moderate, the lack of a patch and the widespread use of WordPress plugins elevate the risk for unmaintained sites.

Deep Dive & Mechanics

The vulnerability resides in the responsive-block-editor-addons plugin, which provides custom Gutenberg blocks for WordPress. The plugin fails to properly sanitize user-supplied input before reflecting it in HTTP responses. An attacker can craft a URL containing malicious JavaScript code in a parameter (e.g., a search query or error message) that the plugin echoes back without escaping. When a victim clicks the link, the script executes in their browser context, potentially leading to session hijacking, defacement, or redirection to malicious sites.

Root Cause: The plugin uses functions like echo $_GET['param'] or similar without applying WordPress's built-in escaping functions (e.g., esc_html(), esc_attr()). This allows arbitrary HTML/JavaScript injection.

Attack Flow:

1. Attacker crafts a malicious URL: https://victim-site.com/?responsive_blocks_error=<script>alert('XSS')</script>
2. Victim clicks the link (e.g., via phishing email).
3. The plugin processes the responsive_blocks_error parameter and reflects it in the page without sanitization.
4. The browser executes the injected script, performing actions on behalf of the victim.

Vulnerable vs. Patched Code

Since no patch is available, the following is a hypothetical comparison based on common XSS fixes.

Vulnerable Code (example):

// In responsive-block-editor-addons.php or similar
$error = $_GET['responsive_blocks_error'];
if ($error) {
    echo '<div class="error">' . $error . '</div>';
}

Patched Code (hypothetical):

$error = isset($_GET['responsive_blocks_error']) ? sanitize_text_field($_GET['responsive_blocks_error']) : '';
if ($error) {
    echo '<div class="error">' . esc_html($error) . '</div>';
}

The patched version uses sanitize_text_field() to strip dangerous characters and esc_html() to encode HTML entities, preventing script execution.

Exploitation & Lab Setup

Red Team (Offensive)

Prerequisites:

• A WordPress site with Responsive Blocks plugin version <= 1.9.9.
• A web browser or tool like curl.

Exploitation Steps:

1. Identify a vulnerable parameter (e.g., responsive_blocks_error or similar). Use a web proxy or fuzzer to discover reflected input.
2. Craft a payload:

   https://victim-site.com/?responsive_blocks_error=<script>alert(document.cookie)</script>
   

3. Send the link to the victim via email or social engineering.
4. Upon click, the script executes, stealing cookies or performing other actions.

Example with curl:

curl -v "http://victim-site.com/?responsive_blocks_error=%3Cscript%3Ealert(1)%3C/script%3E"

Blue Team (Defensive)

Detection:

• Monitor web server logs for unusual query parameters containing <script>, onerror, javascript:, etc.
• Use WAF rules to block reflected XSS patterns.
• Deploy Content Security Policy (CSP) headers to mitigate impact.

Mitigation:

• Disable the plugin until a patch is released.
• Implement input validation and output encoding in custom code.
• Use WordPress security plugins (e.g., Wordfence) to block malicious requests.

Indicators of Compromise (IOCs)

• URL Patterns: Requests containing responsive_blocks_error= or similar parameters with encoded HTML/JavaScript.
• Log Entries: HTTP 200 responses with injected script tags in the body.
• Network Traffic: Outbound connections to attacker-controlled domains from the victim's browser.
• File Hashes: Modified plugin files (e.g., responsive-block-editor-addons.php) with suspicious content.

Detection Engineering

YARA Rule

rule Detect_Responsive_Blocks_XSS {
    meta:
        description = "Detects reflected XSS attempts against CVE-2025-22697"
        author = "Valters IT"
        date = "2025-04-10"
        reference = "CVE-2025-22697"
    strings:
        $param1 = "responsive_blocks_error="
        $param2 = "responsive_blocks_msg="
        $xss1 = /<script[^>]*>/
        $xss2 = /onerror\s*=\s*['"]/
        $xss3 = /javascript\s*:/
    condition:
        any of ($param*) and any of ($xss*)
}

Sigma Rule

title: Reflected XSS Attempt Against Responsive Blocks Plugin
id: 8a3f7c2e-5d1b-4a9f-8c6e-2b3d1f0a7e9c
status: experimental
description: Detects HTTP requests with XSS payloads targeting the Responsive Blocks plugin
author: Valters IT
date: 2025-04-10
logsource:
    category: webserver
    product: apache
    service: access
detection:
    selection:
        cs-method: 'GET'
        cs-uri-query|contains: 
            - 'responsive_blocks_error='
            - 'responsive_blocks_msg='
        cs-uri-query|re: '(<script|onerror|javascript:)'
    condition: selection
falsepositives:
    - Legitimate use of similar parameters in other plugins
level: high

Suricata Rule

alert http any any -> any any (msg:"CVE-2025-22697 Reflected XSS in Responsive Blocks"; flow:to_server,established; content:"responsive_blocks_error="; http_uri; pcre:"/(<script|onerror|javascript:)/i"; classtype:web-application-attack; sid:1000001; rev:1;)

Remediation & Mitigation

1. Immediate Action: Disable the Responsive Blocks plugin until a patch is released.
2. Workaround: Implement a Web Application Firewall (WAF) rule to block requests containing responsive_blocks_error= with script-like content.
3. Long-term Fix: Apply input validation and output encoding in all plugin code. Use WordPress functions like esc_html(), esc_attr(), and sanitize_text_field().
4. Monitoring: Enable logging for all HTTP requests and review for suspicious patterns.
5. User Education: Train users to avoid clicking suspicious links, especially those containing query parameters.

Valters IT
Securing Digital Frontiers