Vulnerability in Verbb Formie
CVE-2026-52889
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.
Published · last modified .
CVSS v3 metric
CVSS v3 base score 9.8 (Critical). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H.
EPSS exploit prediction
EPSS: 0.013 (68.9th percentile), scored .
Low probability of exploitation in the next 30 days, but still tracked. 69th percentile — 68.9% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.007 · newest: 0.013 · change: +0.006
Affected products
- Verbb Formie — versions < 3.1.27
Weakness classification (CWE)
References
Frequently asked questions
- What is CVE-2026-52889?
- CVE-2026-52889 is a critical-severity vulnerability in Verbb Formie, classified under Improper Neutralization of Special Elements Used in a Template Engine. CVSS score: 9.8/10. Published 2026-08-19.
- How severe is CVE-2026-52889?
- Critical severity. CVSS v3 base score is 9.8 out of 10.