Formie: Server-Side Template Injection in Formie Hidden field defaults (CVE-2026-52889) | HOL Guard CVE

Critical severityCVE-2026-52889GHSA-565M-G33J-JQ96

Formie: Server-Side Template Injection in Formie Hidden field defaults

Answer in brief

CVE-2026-52889 records a Critical severity vulnerability in Formie: Server-Side Template Injection in Formie Hidden field defaults. The current sources do not mark it as known exploited. The current feed maps verbb/formie (composer), verbb/formie (generic). Check affected ranges and fixed versions before updating.

Analysis pending evidence review

HOL Guard separates source facts from reviewed analysis. See the methodology.

Published Aug 19, 2026Updated Aug 19, 2026Source checked Aug 19, 2026First seen by HOL Jul 6, 2026Material review Aug 19, 2026

Upstream Advisory

Key facts

Risk: Critical
Exploitation: Not marked as known exploited
Affected software: 2 mapped packages or products
Fix availability: Available

Why this deserves its current priority

A CVSS score is not reported in the current record. The current sources do not mark it as known exploited. Treat this as a source-backed prioritization signal, not a statement about your environment.

Analysis status

Analysis pending evidence review

Factual feed record only; HOL analysis is not approved for indexing. Read the methodology.

Affected scope and exposure questions

The current feed maps verbb/formie (composer), verbb/formie (generic). Check affected ranges and fixed versions before updating.

Mapped affected packages and fixed versions
Package	Affected range	Fixed version
verbb/formiecomposer	<3.1.27	3.1.27
verbb/formiegeneric	< 3.1.27	Not reported

Recommended response

Check inventory. Check lockfiles and deployed manifests for verbb/formie, verbb/formie.
Review the reported fix. Update verbb/formie to 3.1.27 if you use the affected versions. Test the change in a non-production environment first.

Evidence timeline and material changes

Published upstream
Aug 19, 2026
Evidence: source:cvelist:source_dates:source-dates:record
Source modified
Aug 19, 2026
Evidence: source:cvelist:source_dates:source-dates:record
First seen by HOL
Jul 6, 2026

Sources and claim methodology

Upstream source 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.

Quoted source text, attributed separately from HOL analysis.