Executive brief
The Ninja Forms WordPress plugin, a form-building tool used on many websites, fails to properly validate user input during CSV export of form submissions. This allows unauthenticated attackers to inject malicious PHP objects that administrators will execute. If other vulnerable code (in plugins or themes) provides an attack chain, this can lead to arbitrary file deletion, modification, data theft, or remote code execution on the web server.
Technical details
The plugin deserializes untrusted user-submitted form field values during the CSV export process without proper sanitization, enabling PHP Object Injection (CWE-502). An unauthenticated attacker submits a form containing a serialized PHP object, and when an administrator exports submissions to CSV, the object is unserialized. Exploitation requires a PHP Object Injection gadget chain available in another installed plugin or theme, but the attack is network-accessible and requires no authentication on the attacker side.
Affected products
- Ninja Forms Ninja Forms 3.15.3
Timeline
- 2026-09-22: disclosed
- 2026-09-22: patched: Fixed in version 3.15.4