CVE-2025-13731
📋 TL;DR
This vulnerability allows authenticated WordPress users with Contributor-level access or higher to inject malicious JavaScript into website pages using the 'nxt-year' shortcode. The injected scripts execute whenever other users view the compromised pages, enabling persistent cross-site scripting attacks. All WordPress sites using the Nexter Extension plugin up to version 4.4.1 are affected.
💻 Affected Systems
- Nexter Extension – Site Enhancements Toolkit WordPress plugin
⚠️ Manual Verification Required
This CVE does not have specific version information in our database, so automatic vulnerability detection cannot determine if your system is affected.
Why? The CVE database entry doesn't specify which versions are vulnerable (no version ranges provided by the vendor/NVD).
🔒 Custom verification scripts are available for registered users. Sign up free to download automated test scripts.
- Review the CVE details at NVD
- Check vendor security advisories for your specific version
- Test if the vulnerability is exploitable in your environment
- Consider updating to the latest version as a precaution
⚠️ Risk & Real-World Impact
Worst Case
Attackers could steal administrator credentials, redirect users to malicious sites, deface websites, or perform actions on behalf of authenticated users, potentially leading to complete site compromise.
Likely Case
Attackers with contributor access inject malicious scripts to steal user session cookies, redirect visitors to phishing sites, or display unwanted advertisements.
If Mitigated
With proper user role management and content review processes, the impact is limited to potential defacement of non-critical pages.
🎯 Exploit Status
Exploitation requires authenticated access but is technically simple once an attacker has contributor privileges.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: 4.4.2
Restart Required: No
Instructions:
1. Log into WordPress admin panel. 2. Navigate to Plugins → Installed Plugins. 3. Find 'Nexter Extension – Site Enhancements Toolkit'. 4. Click 'Update Now' if available, or manually update to version 4.4.2. 5. Verify the plugin version shows 4.4.2 or higher.
🔧 Temporary Workarounds
Disable vulnerable shortcode
allRemove or disable the 'nxt-year' shortcode functionality
Add to theme's functions.php: remove_shortcode('nxt-year');
Restrict user roles
allTemporarily restrict Contributor and Author roles from creating/editing posts
Use WordPress role management plugins or custom code to modify capabilities
🧯 If You Can't Patch
- Implement strict content sanitization for all user-generated content using the nxt-year shortcode
- Enable WordPress security plugins with XSS protection and monitor for suspicious shortcode usage
🔍 How to Verify
Check if Vulnerable:
Check WordPress admin → Plugins → Installed Plugins, find Nexter Extension plugin and verify version is 4.4.1 or lowerCheck Version:
wp plugin list --name='nexter-extension' --field=versionVerify Fix Applied:
Confirm plugin version is 4.4.2 or higher in WordPress admin panel📡 Detection & Monitoring
Log Indicators:
- Unusual shortcode usage patterns in post/page edits
- Multiple failed login attempts followed by successful contributor login
Network Indicators:
- Unexpected JavaScript payloads in HTTP responses containing 'nxt-year'
SIEM Query:
source="wordpress.log" AND "nxt-year" AND ("script" OR "javascript" OR "onclick")🔗 References
- https://plugins.trac.wordpress.org/browser/nexter-extension/trunk/include/class-nexter-load-ext.php#L136
- https://plugins.trac.wordpress.org/browser/nexter-extension/trunk/include/class-nexter-load-ext.php#L66
- https://plugins.trac.wordpress.org/changeset?old=3402155&old_path=nexter-extension%2Ftags%2F4.4.1%2Finclude%2Fclass-nexter-load-ext.php&new=3403967&new_path=nexter-extension%2Ftags%2F4.4.2%2Finclude%2Fclass-nexter-load-ext.php
- https://www.wordfence.com/threat-intel/vulnerabilities/id/809cd97c-22ea-49e7-be46-688fefe50236?source=cve
