A critical vulnerability in the Ninja Forms – File Upload plugin has left approximately 50,000 WordPress websites exposed to unauthenticated arbitrary file upload attacks, potentially leading to remote code execution (RCE) and full site takeover.
Vulnerability Details
- CVE: CVE-2026-0740
- Severity: CVSS score of 9.8 (Critical)
- Type: Unauthenticated arbitrary file upload
- Discovered by: Security researcher Sélim Lanouar (awarded $2,145 bug bounty)
- Affected versions: Up to and including 3.3.26
Exploitation Path
- The vulnerable
handle_upload()function calls_process()to move uploaded files. - Oversight: Destination filename extensions are not validated, and filenames are not sanitized.
- Impact: Attackers can upload malicious
.phpfiles (webshells) into the root directory. - Result: Full compromise of the site, including:
- Executing terminal commands on the server.
- Stealing sensitive database information.
- Injecting malware into legitimate pages.
- Redirecting visitors to malicious sites.
- Using compromised servers for further attacks.
Mitigation Timeline
- Jan 8, 2026: Wordfence rolled out firewall protections for premium users.
- Feb 7, 2026: Protections extended to free users.
- Mar 19, 2026: Plugin developers released version 3.3.27, which fully patched the flaw.
Defensive Guidance
- Update immediately: Upgrade Ninja Forms File Upload to version 3.3.27 or higher.
- Monitor logs: Check for suspicious
.phpuploads or path traversal attempts. - Harden WordPress:
- Restrict file upload permissions.
- Use a web application firewall (WAF).
- Regularly back up site data.
- Stay alert: Automated web-scanning scripts are actively probing for unpatched sites.
Final Thought
This vulnerability is particularly dangerous because it requires no authentication and is trivial to exploit. With 50,000 sites at risk, administrators must act quickly to patch and secure their WordPress environments. In the age of automated exploitation, delayed updates equal guaranteed compromise.
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