# Ninja Forms <= 3.15.5 - Unauthenticated Stored Cross-Site Scripting via Submission 'calculations' Extra Data

- **ID:** WPSEC-2026-1133
- **Plugin:** Ninja Forms – Contact Form Builder with Calculators, Quizzes, Signatures & AI Form Builder (`ninja-forms`), https://wordpress.org/plugins/ninja-forms/
- **Affected versions:** all versions before 3.15.6
- **Fixed in:** 3.15.6 (Update to 3.15.6 or later.)
- **Severity:** High 7.2 (CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:L/I:L/A:N)
- **Weakness:** CWE-79
- **Usage among sites WPSec scans:** plugin Medium, affected versions Medium (as of 2026-10-16)
- **Attack surface analysis:** https://attacksurface.wpsec.com/plugin/ninja-forms
- **Fix released:** 2026-10-15
- **Published:** 2026-10-16
- **URL:** https://wpsec.com/vuln/WPSEC-2026-1133/

## Description

The Ninja Forms plugin for WordPress is vulnerable to Stored Cross-Site Scripting via submission extra data in all versions up to, and including, 3.15.5. This is due to an incomplete check on the reserved, server-generated 'calculations' extra-data key and missing output escaping of calculation names in the admin submission Calculations metabox. The plugin removes only an exact 'calculations' key. A key containing a backslash passes that check, and update_post_meta() then unslashes it to 'calculations'. This makes it possible for unauthenticated attackers to inject arbitrary web scripts that execute whenever an administrator views the affected submission.

## References

- https://wpsec.com/vuln/WPSEC-2026-1133/
- https://plugins.svn.wordpress.org/ninja-forms/tags/3.15.6/
- https://wordpress.org/plugins/ninja-forms/

Source: WPSec, https://wpsec.com/vuln/WPSEC-2026-1133/

License: CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Free to use, share and adapt, also commercially, if you credit WPSec and link to this advisory.