CVE-2025-66111
📋 TL;DR
This stored cross-site scripting (XSS) vulnerability in the Nelio Popups WordPress plugin allows attackers to inject malicious scripts into web pages that are then executed when other users view those pages. The vulnerability affects all WordPress sites using Nelio Popups version 1.3.0 or earlier. Attackers can steal session cookies, redirect users to malicious sites, or perform actions on behalf of authenticated users.
💻 Affected Systems
- Nelio Popups 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 session cookies, take over WordPress sites, install backdoors, deface websites, or redirect visitors to malicious sites containing malware.
Likely Case
Attackers inject malicious JavaScript to steal user session cookies, potentially compromising user accounts and performing unauthorized actions on the site.
If Mitigated
With proper input validation and output encoding, malicious scripts would be neutralized before reaching users, preventing execution.
🎯 Exploit Status
Stored XSS vulnerabilities are commonly exploited. The vulnerability requires some level of access to inject payloads, but exploitation is straightforward once access is obtained.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: 1.3.1 or later
Restart Required: No
Instructions:
1. Log into WordPress admin panel. 2. Navigate to Plugins → Installed Plugins. 3. Find Nelio Popups and click 'Update Now'. 4. Alternatively, download latest version from WordPress repository and replace plugin files.
🔧 Temporary Workarounds
Disable Plugin
allTemporarily disable the vulnerable plugin until patched
wp plugin deactivate nelio-popups
Content Security Policy
allImplement CSP headers to restrict script execution
Add to .htaccess: Header set Content-Security-Policy "default-src 'self'; script-src 'self'"
Add to wp-config.php: header("Content-Security-Policy: default-src 'self'; script-src 'self'");
🧯 If You Can't Patch
- Remove the Nelio Popups plugin completely from your WordPress installation
- Implement web application firewall (WAF) rules to block XSS payloads targeting this plugin
🔍 How to Verify
Check if Vulnerable:
Check WordPress admin → Plugins → Installed Plugins for Nelio Popups version. If version is 1.3.0 or earlier, you are vulnerable.Check Version:
wp plugin get nelio-popups --field=versionVerify Fix Applied:
After updating, verify Nelio Popups version shows 1.3.1 or later in WordPress plugins list.📡 Detection & Monitoring
Log Indicators:
- Unusual POST requests to plugin endpoints containing script tags or JavaScript
- Multiple failed login attempts followed by plugin modification requests
Network Indicators:
- HTTP requests containing malicious script payloads in parameters
- Outbound connections to suspicious domains from your WordPress site
SIEM Query:
source="wordpress.log" AND ("nelio-popups" OR "nelio_popups") AND ("<script>" OR "javascript:" OR "onerror=" OR "onload=")