CVE-2026-71291 — Bolt CMS renders content field values through Twig's full application-level Environment…¶

Key facts

CVE-2026-71291 is a High (8.8) vulnerability: Bolt CMS renders content field values through Twig's full application-level Environment…. This entry ships a detection-only PoC and a Docker test lab.


CVE	CVE-2026-71291
Severity	High (8.8)
Detection / prevention	—
PoC	poc.py
Source	2026/CVE-2026-71291/

Details¶

English | 한국어

Description¶

Bolt CMS renders content field values through Twig's full application-level Environment with no SandboxExtension registered anywhere in the codebase. In src/Entity/Field.php, getTwigValue() calls shouldBeRenderedAsTwig(), which gates rendering only on the field definition's allow_twig flag and a regex checking for {{, {%, or {#; when true, the raw field value is compiled and rendered via self::getTwig()->createTemplate($value)->render(['record' => $this->getContent()]) with no sandboxing. Bolt's own bundled config/bolt/contenttypes.yaml sets allow_twig: true on the default "pages" contenttype's content field out of the box. Any user with edit access to that content type (a standard editor role, not just an administrator) can inject a Twig payload such as {{ ['id']|map('passthru')|join }} that executes arbitrary OS commands when the content is saved and rendered, achieving remote code execution as the web server user.

Vulnerability Details¶

Property	Value
CVE ID	CVE-2026-71291
Type	RCE
CVSS Score	8.8

Proof of Concept¶

Download¶

# Download PoC script
curl -O https://raw.githubusercontent.com/fankh/vulnerability-poc/main/2026/CVE-2026-71291/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-2026-71291

# 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/bolt/core
https://github.com/bolt/core/blob/6.1/src/Entity/Field.php

Generated by PoC Generator on 2026-08-09T17:58:56.7113589

Frequently asked questions¶

What is CVE-2026-71291?¶

CVE-2026-71291 is a High (8.8) vulnerability: Bolt CMS renders content field values through Twig's full application-level Environment…. This entry ships a detection-only PoC and a Docker test lab.

How do I detect CVE-2026-71291?¶

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-2026-71291?¶

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.