Vulnerability · Published Aug 19, 2026 · Assigned by GitHub_M
CVE-2026-52889Formie: Server-Side Template Injection in Formie Hidden field defaults
Critical 9.8
In plain English
A critical-severity security flaw in formie from verbb. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 1.3% (higher than 70% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.
Official description
Formie is a Craft CMS plugin for creating forms. Prior to 3.1.27, Formie can pass request-derived Hidden field defaults such as HTTP User Agent, Referer URL, Current URL, Current URL without Query String, Query Parameter, and Cookie Value to Craft's Twig rendering layer during front-end form rendering. An unauthenticated attacker can place Twig syntax in one of these request-controlled inputs when a public form contains an affected Hidden field. Hidden::getFrontEndInputOptions() then assigns the value to defaultValue and calls renderString, causing server-side template evaluation rather than treating the request data as a plain string. Depending on the Craft site configuration and available Twig capabilities, exploitation can disclose sensitive information, modify application state, or achieve remote code execution. This issue is fixed in version 3.1.27.
Affected packages & fixed versions
| Ecosystem | Package | Fixed in | Advisory |
|---|---|---|---|
| Packagist | verbb/formie | 3.1.27 | GHSA-565m-g33j-jq96 |
Affected products (as reported)
Weakness: CWE-1336 · Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
References
- https://github.com/verbb/formie/security/advisories/GHSA-565m-g33j-jq96 x_refsource_CONFIRM
- https://github.com/verbb/formie/commit/d3b9d15290405e484e3b5c91c5d8fab93047f9b2 x_refsource_MISC
- https://github.com/verbb/formie/releases/tag/3.1.27 x_refsource_MISC