CVE-2024-4268
📋 TL;DR
This vulnerability allows authenticated WordPress users with contributor-level access or higher to inject malicious scripts into website pages using the Ultimate Blocks plugin. The scripts execute whenever users view the compromised pages, enabling attackers to steal session cookies, redirect users, or deface websites. All WordPress sites using Ultimate Blocks plugin versions up to 3.1.9 are affected.
💻 Affected Systems
- Ultimate Blocks – WordPress Blocks Plugin
📦 What is this software?
⚠️ Risk & Real-World Impact
Worst Case
Attackers could steal administrator session cookies, take over the WordPress site, install backdoors, redirect users to malicious sites, or deploy ransomware-like defacement.
Likely Case
Attackers inject malicious JavaScript to steal user session cookies, redirect visitors to phishing sites, or display unwanted advertisements.
If Mitigated
With proper user access controls and content security policies, impact is limited to defacement of specific pages rather than site-wide compromise.
🎯 Exploit Status
Exploitation requires authenticated access but is technically simple. Public proof-of-concept code is available in the provided references.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: 3.2.0 or later
Vendor Advisory: https://wordpress.org/plugins/ultimate-blocks/#developers
Restart Required: No
Instructions:
1. Log into WordPress admin panel. 2. Navigate to Plugins → Installed Plugins. 3. Find Ultimate Blocks plugin. 4. Click 'Update Now' if update is available. 5. If no update appears, manually download version 3.2.0+ from WordPress.org and replace plugin files.
🔧 Temporary Workarounds
Disable Ultimate Blocks Plugin
allTemporarily deactivate the vulnerable plugin until patched
wp plugin deactivate ultimate-blocks
Restrict User Roles
linuxRemove contributor-level access from untrusted users
wp user list --role=contributor --field=ID | xargs wp user set-role subscriber
🧯 If You Can't Patch
- Implement Content Security Policy (CSP) headers to restrict script execution
- Enable WordPress security plugins that filter malicious content and monitor for XSS attempts
🔍 How to Verify
Check if Vulnerable:
Check WordPress admin → Plugins → Ultimate Blocks → Version number. If version is 3.1.9 or lower, you are vulnerable.Check Version:
wp plugin get ultimate-blocks --field=versionVerify Fix Applied:
After updating, verify version is 3.2.0 or higher. Test plugin blocks to ensure they properly sanitize HTML attributes.📡 Detection & Monitoring
Log Indicators:
- Unusual POST requests to wp-admin/post.php with script tags in parameters
- Multiple page edits from single contributor accounts in short timeframes
Network Indicators:
- Outbound connections to unknown domains from your WordPress site
- Unexpected JavaScript includes in page responses
SIEM Query:
source="wordpress.log" AND ("script" OR "onclick" OR "javascript:") AND "post_content"🔗 References
- https://gist.github.com/webber-naut/0a8a4f810da286392a43c4614d31712e
- https://plugins.trac.wordpress.org/browser/ultimate-blocks/trunk/src/blocks/advanced-heading/block.php
- https://plugins.trac.wordpress.org/browser/ultimate-blocks/trunk/src/blocks/how-to/block.php
- https://plugins.trac.wordpress.org/browser/ultimate-blocks/trunk/src/blocks/image-slider/block.php
- https://plugins.trac.wordpress.org/browser/ultimate-blocks/trunk/src/blocks/styled-box/block.php
- https://plugins.trac.wordpress.org/browser/ultimate-blocks/trunk/src/blocks/testimonial/block.php
- https://plugins.trac.wordpress.org/browser/ultimate-blocks/trunk/src/extensions/custom-css/class-custom-css.php?rev=3102541#L173
- https://plugins.trac.wordpress.org/changeset/3075315/ultimate-blocks
- https://plugins.trac.wordpress.org/changeset/3108401/
- https://wordpress.org/plugins/ultimate-blocks/#developers
- https://www.dropbox.com/scl/fi/zh7t1qsvxkxk2dfhwd7nn/Ultimate-Blocks-Stored-XSS_POC_4.20.24.mov?rlkey=ws16dcu7f6mjd3h9emsqev7jm&e=2&st=fdr7q9h7&dl=0
- https://www.wordfence.com/threat-intel/vulnerabilities/id/00b60b53-77bf-4640-bf2b-84e011014623?source=cve
- https://gist.github.com/webber-naut/0a8a4f810da286392a43c4614d31712e
- https://plugins.trac.wordpress.org/browser/ultimate-blocks/trunk/src/blocks/advanced-heading/block.php
- https://plugins.trac.wordpress.org/browser/ultimate-blocks/trunk/src/blocks/how-to/block.php
- https://plugins.trac.wordpress.org/browser/ultimate-blocks/trunk/src/blocks/image-slider/block.php
- https://plugins.trac.wordpress.org/browser/ultimate-blocks/trunk/src/blocks/styled-box/block.php
- https://plugins.trac.wordpress.org/browser/ultimate-blocks/trunk/src/blocks/testimonial/block.php
- https://plugins.trac.wordpress.org/browser/ultimate-blocks/trunk/src/extensions/custom-css/class-custom-css.php?rev=3102541#L173
- https://plugins.trac.wordpress.org/changeset/3075315/ultimate-blocks
- https://plugins.trac.wordpress.org/changeset/3108401/
- https://wordpress.org/plugins/ultimate-blocks/#developers
- https://www.dropbox.com/scl/fi/zh7t1qsvxkxk2dfhwd7nn/Ultimate-Blocks-Stored-XSS_POC_4.20.24.mov?rlkey=ws16dcu7f6mjd3h9emsqev7jm&e=2&st=fdr7q9h7&dl=0
- https://www.wordfence.com/threat-intel/vulnerabilities/id/00b60b53-77bf-4640-bf2b-84e011014623?source=cve
