# CVE-2026-103909: Calculated Fields Form reflected DOM-based XSS in URL parameters

Source: https://junglewise.ai/threats/cve-2026-103909-the-calculated-fields-form-ai-form-builder-for-wordpress-contact  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-10-03. Updated: 2026-10-05  
License: CC BY 4.0 with a link back

CVE-2026-103909 · Severity: medium · CVSS 6.1 · Published 2026-10-03

The Calculated Fields Form plugin for WordPress is used to create contact forms, payment forms, quizzes, and other dynamic web forms. An attacker can inject malicious JavaScript code by crafting a malicious link if a form administrator has configured certain URL parameter fields together in a calculation. When an unsuspecting user clicks such a link, the injected script runs in their browser, potentially stealing session cookies, credentials, or performing actions on behalf of the user.

Technologies: [Calculated Fields Form](https://junglewise.ai/threats/technologies/calculated-fields-form). Vendors: [Calculated Fields Form](https://junglewise.ai/threats/vendors/calculated-fields-form).

## Quick answers

**Is CVE-2026-103909 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-103909 being exploited in the wild.

**How severe is CVE-2026-103909?** Medium severity, with a CVSS score of 6.1, published 3 October 2026.

**Which products and versions are affected?** Calculated Fields Form up to and including 5.5.1.5.

**Is there a fix for CVE-2026-103909?** No fixed version is recorded yet. Check the vendor's advisory in the references below. If you run it, Junglewise drafts a mitigation that fits your setup and applies it once you approve, with senior security engineers behind it.

**How is CVE-2026-103909 attacked?** It is attacked over the network, in a web application.

**Am I affected by CVE-2026-103909?** Check whether you run Calculated Fields Form at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## Technical details

This is a reflected DOM-based cross-site scripting (XSS) vulnerability affecting the Calculated Fields Form WordPress plugin through version 5.5.1.5. The vulnerability exists in the handling of arbitrary URL parameters (url.<name>) in form equations due to insufficient input sanitization and output escaping in the client-side JavaScript. An unauthenticated attacker can inject arbitrary JavaScript via crafted URL parameters, though exploitation requires a specific configuration where an administrator has concatenated at least two url.<name> fields in a form equation.

## Affected products

- Calculated Fields Form Calculated Fields Form up to and including 5.5.1.5

## Timeline

- 2026-10-03: disclosed

## References

- [https://plugins.trac.wordpress.org/browser/calculated-fields-form/tags/5.5.1.5/js/fbuilder-pro-public.jquery.js](https://plugins.trac.wordpress.org/browser/calculated-fields-form/tags/5.5.1.5/js/fbuilder-pro-public.jquery.js)
- [https://plugins.trac.wordpress.org/browser/calculated-fields-form/tags/5.5.1.5/js/fbuilder-pro-public.jquery.js](https://plugins.trac.wordpress.org/browser/calculated-fields-form/tags/5.5.1.5/js/fbuilder-pro-public.jquery.js)

## Related threats

- [Calculated Fields Form plugin reflected DOM-based XSS](https://junglewise.ai/threats/cve-2026-100184-the-calculated-fields-form-ai-form-builder-for-wordpress-contact)
- [Calculated Fields Form plugin for WordPress reflected DOM XSS](https://junglewise.ai/threats/cve-2026-100179-the-calculated-fields-form-ai-form-builder-for-wordpress-contact)
- [Calculated Fields Form cross-site scripting in form handling](https://junglewise.ai/threats/cve-2026-95529-unauthenticated-cross-site-scripting-xss-in-calculated-fields)