# CVE-2026-52889: Verbb Formie server-side template injection in Hidden fields

Source: https://junglewise.ai/threats/cve-2026-52889-verbb-formie-server-side-template-injection-in-hidden-fields  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-07-06. Updated: 2026-07-06  
License: CC BY 4.0 with a link back

CVE-2026-52889 · Severity: critical · CVSS 9.8 · Published 2026-07-06

Formie, a form-building plugin for the Craft CMS, contains a vulnerability in how it handles hidden form fields. An attacker can send specially crafted web requests that trick the server into executing malicious code when a form is displayed to a user. This could allow an unauthorized person to steal sensitive data, modify website content, or take full control of the server.

Technologies: [verbb/formie (Packagist)](https://junglewise.ai/threats/technologies/verbb-formie), [Verbb Formie](https://junglewise.ai/threats/technologies/formie). Vendors: [Packagist](https://junglewise.ai/threats/vendors/packagist), [Verbb](https://junglewise.ai/threats/vendors/verbb).

## Quick answers

**Is CVE-2026-52889 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-52889 being exploited in the wild.

**How severe is CVE-2026-52889?** Critical severity, with a CVSS score of 9.8, published 6 July 2026.

**Which products and versions are affected?** verbb/formie (Packagist) < 3.1.27, ECOSYSTEM:introduced=0,fixed=3.1.27; Verbb Formie >= 3.0.0-beta.1, <= 3.1.26.

**Is there a fix for CVE-2026-52889?** Yes. verbb/formie (Packagist): upgrade to 3.1.27 or later. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2026-52889 attacked?** It is attacked over the network, in a software library.

**Am I affected by CVE-2026-52889?** Check whether you run verbb/formie (Packagist) or Verbb Formie 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.

## How to fix

- verbb/formie (Packagist): upgrade to 3.1.27 or later

  ```sh
  composer require verbb/formie:^3.1.27
  ```


## Technical details

A Server-Side Template Injection (SSTI) vulnerability exists in the front-end rendering path of Formie's Hidden fields. When a Hidden field is configured to use dynamic default values (such as User-Agent, Referer, or Query Parameters), the application fails to sanitize these request-derived values before passing them to the Twig rendering engine in `Hidden::getFrontEndInputOptions()`. An unauthenticated remote attacker can inject Twig syntax into these request headers or parameters, leading to arbitrary code execution or sensitive information disclosure within the Craft CMS environment. The vulnerability is patched in version 3.1.27 by treating request-derived values as plain strings rather than template sources.

## Affected products

- Verbb Formie >= 3.0.0-beta.1, <= 3.1.26

## Identifiers

- CVE-2026-52889
- GHSA-565m-g33j-jq96

## Timeline

- 2026-05-30: disclosed
- 2026-05-30: advisory
- 2026-07-06: patched: Date of reviewed advisory publication confirming patch version 3.1.27

## References

- [https://github.com/verbb/formie/security/advisories/GHSA-565m-g33j-jq96](https://github.com/verbb/formie/security/advisories/GHSA-565m-g33j-jq96)
- [https://api.github.com/repos/verbb/formie/security-advisories/GHSA-565m-g33j-jq96](https://api.github.com/repos/verbb/formie/security-advisories/GHSA-565m-g33j-jq96)

## Related threats

- [Verbb Formie missing authorization on sent notification resend modal](https://junglewise.ai/threats/cve-2026-76089-verbb-formie-missing-authorization-on-sent-notification-resend)
- [Verbb Formie unauthenticated submission hijacking via submit action](https://junglewise.ai/threats/cve-2026-76087-verbb-formie-unauthenticated-submission-hijacking-via-submit)
- [Craft Formie integration form-settings SSRF and credential exfiltration](https://junglewise.ai/threats/cve-2026-76086-craft-formie-integration-form-settings-ssrf-and-credential)
- [Verbb Formie missing authorization in administrative settings](https://junglewise.ai/threats/verbb-formie-missing-authorization-in-administrative-settings-0ab8bf10)
- [Verbb Formie authorization bypass in form submissions](https://junglewise.ai/threats/cve-2026-47266-verbb-formie-authorization-bypass-in-form-submissions)