# CVE-2026-78838: AppNitro MachForm reflected XSS in grid_datasource.php

Source: https://junglewise.ai/threats/cve-2026-78838-appnitro-machform-reflected-xss-in-grid-datasource-php  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-09-08. Updated: 2026-09-26  
License: CC BY 4.0 with a link back

CVE-2026-78838 · Severity: medium · CVSS 6.5 · Published 2026-09-08

MachForm is a web-based form builder and management platform used by businesses to create and deploy online forms. An unauthenticated attacker can inject malicious JavaScript into form requests, allowing them to steal session cookies, perform actions on behalf of victims, or redirect users to phishing pages when they click a crafted link.

Technologies: [AppNitro MachForm](https://junglewise.ai/threats/technologies/machform). Vendors: [AppNitro](https://junglewise.ai/threats/vendors/appnitro).

## Quick answers

**Is CVE-2026-78838 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-78838 being exploited in the wild.

**How severe is CVE-2026-78838?** Medium severity, with a CVSS score of 6.5, published 8 September 2026.

**Which products and versions are affected?** AppNitro MachForm v30.

**Is there a fix for CVE-2026-78838?** 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-2026-78838 attacked?** It is attacked over the network.

**Am I affected by CVE-2026-78838?** Check whether you run AppNitro MachForm 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

A reflected cross-site scripting (XSS) vulnerability exists in the grid_datasource.php component due to insufficient input validation on the filter[filters][0][field] parameter. The vulnerability is triggered when an unauthenticated attacker crafts a malicious URL containing JavaScript payload, which is reflected in the response without proper sanitization. The attack requires no authentication and relies on user interaction (victim clicking the link), and allows arbitrary JavaScript execution in the victim's browser context. The fix involves proper output encoding and input validation on the vulnerable parameter.

## Affected products

- AppNitro MachForm v30

## Timeline

- 2026-09-08: disclosed

## References

- [https://github.com/nabeelmkhan/CVE-2026-78838](https://github.com/nabeelmkhan/CVE-2026-78838)
- [https://packetstormsecurity.com/](https://packetstormsecurity.com/)

## Related threats

- [AppNitro MachForm SQL injection in ap_form parameter](https://junglewise.ai/threats/cve-2026-78837-appnitro-machform-sql-injection-in-ap-form-parameter)
- [AppNitro MachForm arbitrary file upload leading to code execution](https://junglewise.ai/threats/cve-2026-78839-appnitro-machform-arbitrary-file-upload-leading-to-code-execution)