CVE-2026-52889 — Formie is a Craft CMS plugin for creating forms.¶
Key facts
CVE-2026-52889 is a Critical (9.8) vulnerability: Formie is a Craft CMS plugin for creating forms.. This entry ships a detection-only PoC and a Docker test lab.
| CVE | CVE-2026-52889 |
| Severity | Critical (9.8) |
| Detection / prevention | — |
| PoC | poc.py |
| Source | 2026/CVE-2026-52889/ |
Details¶
English | 한국어
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.
Vulnerability Details¶
| Property | Value |
|---|---|
| CVE ID | CVE-2026-52889 |
| Type | RCE |
| CVSS Score | 9.8 |
Proof of Concept¶
Download¶
# Download PoC script
curl -O https://raw.githubusercontent.com/fankh/vulnerability-poc/main/2026/CVE-2026-52889/poc.py
Usage¶
# Run PoC against target
python3 poc.py --target <TARGET_URL>
# With authentication
python3 poc.py --target <TARGET_URL> --username <USER> --password <PASS>
⚠️ Warning: This PoC is for authorized security testing only. It uses detection-only techniques and does not exploit or damage target systems.
Test Lab¶
This repository includes a Docker-based test environment with both vulnerable and patched applications.
Quick Start¶
# Clone and navigate to CVE directory
cd CVE-2026-52889
# Start both applications
docker-compose up -d
# Run tests
./run-tests.sh # Linux/Mac
./run-tests.ps1 # Windows PowerShell
Application Endpoints¶
| Application | URL | Status |
|---|---|---|
| Vulnerable App | http://localhost:8080 | Shows vulnerability |
| Patched App | http://localhost:8081 | Demonstrates fix |
Directory Structure¶
├── README.md # English documentation
├── README_KO.md # Korean documentation
├── poc.py # PoC detection script
├── docker-compose.yml # Container orchestration
├── run-tests.sh # Linux/Mac test runner
├── run-tests.ps1 # Windows test runner
├── vulnerable-app/ # Vulnerable version
│ ├── app.py
│ ├── Dockerfile
│ └── requirements.txt
└── patched-app/ # Fixed version
├── app.py
├── Dockerfile
└── requirements.txt
References¶
- https://github.com/verbb/formie/commit/d3b9d15290405e484e3b5c91c5d8fab93047f9b2
- https://github.com/verbb/formie/releases/tag/3.1.27
- https://github.com/verbb/formie/security/advisories/GHSA-565m-g33j-jq96
Generated by PoC Generator on 2026-08-24T15:34:05.775907905
Frequently asked questions¶
What is CVE-2026-52889?¶
CVE-2026-52889 is a Critical (9.8) vulnerability: Formie is a Craft CMS plugin for creating forms.. This entry ships a detection-only PoC and a Docker test lab.
How do I detect CVE-2026-52889?¶
Run the detection-only PoC included with this entry against your Docker test lab to confirm whether a target is affected; pair it with your own IDS logging.
How do I block or mitigate CVE-2026-52889?¶
Upgrade to a fixed version per the vendor advisory; the NVD record lists the affected versions. Use the included PoC to verify your remediation.
For authorized security testing and research only. See the full source and NVD record.