Executive brief
Ninja Forms, a popular WordPress plugin for creating web forms, stores user-submitted textarea content without properly encoding it. When an administrator views submissions containing malicious code, the attacker's script runs with the administrator's privileges, potentially allowing account takeover or data theft.
Technical details
A stored cross-site scripting (XSS) vulnerability exists in Ninja Forms 3.15.3 where non-RTE textarea fields fail to HTML-encode submitted values before rendering them in the legacy submission editor. An unauthenticated attacker can inject JavaScript that breaks out of the textarea element; when an authenticated WordPress administrator opens the attacker-controlled submission URL, the payload executes in the WordPress admin context.
Affected products
- Ninja Forms Ninja Forms 3.15.3
Timeline
- 2026-09-22: disclosed