Formie: Pre-authenticated server-side template injection in Hidden fields

published 2026-05-18 5 mo ago modified 2026-09-10 1 mo ago also GHSA-x7m9-mwc2-g6w2 , EUVD-2026-33421

cvss: 9.8; version 3.1, CNA
cisa kev: Not listed; not in CISA's catalog
epss: 0.5%; EPSS 0.5% chance of exploitation in 30 days, percentile 41%
public exploits: 0; none known

Formie is a Craft CMS plugin for creating forms. Prior to 2.2.20 and 3.1.24, unauthenticated users could submit crafted values into Hidden fields (with Default value → Custom) that were evaluated as Twig during submission handling, which could lead to serious compromise of the Craft site (depending on template/sandbox behavior). This vulnerability is fixed in 2.2.20 and 3.1.24.

Patch / fix

fixed in 1 links 3

packagist verbb/formie 2.2.20, 3.1.24

github.com/verbb/formie@f690d56 commit
github.com/verbb/formie/releases/tag/2.2.20 release
github.com/verbb/formie/releases/tag/3.1.24 release

CISA SSVC

Exploitation: none
Automatable: yes
Technical impact: total
Assessed: 5 mo ago (2026-06-01)

Exploit prediction

0.47% chance of exploitation in the next 30 days, higher than 41% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by	version	score	vector
CNA	3.1	9.8	CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
GitHub	3.1	9.8	CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Affected packages

ecosystem	package	affected	fixed in
packagist	verbb/formie	>=3.0.0-beta.1, <3.1.24 <2.2.20	3.1.24 2.2.20

Affected products

verbb formie

Classification

Weakness

CWE-94 Improper Control of Generation of Code
CWE-693 Protection Mechanism Failure
CWE-1336 Improper Neutralization of Special Elements Used in a Template Engine

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.

Summary