CVE-2025-0521
📋 TL;DR
The Post SMTP WordPress plugin has a stored cross-site scripting vulnerability that allows unauthenticated attackers to inject malicious scripts into email from/subject fields. These scripts execute when users view affected pages, potentially compromising their browsers. All WordPress sites using Post SMTP version 3.0.2 or earlier are affected.
💻 Affected Systems
- Post SMTP WordPress Plugin
📦 What is this software?
Post Smtp by Wpexperts
⚠️ Risk & Real-World Impact
Worst Case
Attackers could steal administrator session cookies, redirect users to malicious sites, or perform actions on behalf of authenticated users, potentially leading to full site compromise.
Likely Case
Attackers inject malicious scripts that steal user session data or credentials when users view email-related pages, leading to account compromise.
If Mitigated
With proper web application firewalls and content security policies, script execution could be blocked, limiting impact to script injection without execution.
🎯 Exploit Status
Exploitation requires no authentication and involves simple script injection into email fields.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Version 3.0.3 or later
Restart Required: No
Instructions:
1. Log into WordPress admin panel. 2. Navigate to Plugins > Installed Plugins. 3. Find Post SMTP plugin. 4. Click 'Update Now' if update available. 5. If no update appears, manually download version 3.0.3+ from WordPress.org and replace plugin files.
🔧 Temporary Workarounds
Temporary Plugin Deactivation
WordPressDisable the Post SMTP plugin until patched to prevent exploitation.
wp plugin deactivate post-smtp
🧯 If You Can't Patch
- Implement a Web Application Firewall (WAF) with XSS protection rules
- Add Content Security Policy headers to restrict script execution sources
🔍 How to Verify
Check if Vulnerable:
Check WordPress admin panel > Plugins > Installed Plugins for Post SMTP version number.Check Version:
wp plugin get post-smtp --field=versionVerify Fix Applied:
Verify Post SMTP plugin version is 3.0.3 or higher in WordPress admin panel.📡 Detection & Monitoring
Log Indicators:
- Unusual POST requests to email-related endpoints with script tags in parameters
- Multiple failed script injection attempts in web server logs
Network Indicators:
- HTTP requests containing script tags in from/subject parameters to WordPress email endpoints
SIEM Query:
source="web_server_logs" AND (uri_path="*admin-ajax.php*" OR uri_path="*wp-admin*" OR uri_path="*post-smtp*") AND (http_params CONTAINS "<script>" OR http_params CONTAINS "javascript:")