CVE-2026-85604 — Grav before 2.0.19 (affected versions <= 2.0.17) contains a remote code execution…¶

Q: What is CVE-2026-85604?

CVE-2026-85604 is a High (8.8) vulnerability: Grav before 2.0.19 (affected versions <= 2.0.17) contains a remote code execution…. This entry ships a detection-only PoC and a Docker test lab.

Q: How do I detect CVE-2026-85604?

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.

Q: How do I block or mitigate CVE-2026-85604?

Upgrade to a fixed version per the vendor advisory; the NVD record lists the affected versions. Use the included PoC to verify your remediation.

Key facts

CVE-2026-85604 is a High (8.8) vulnerability: Grav before 2.0.19 (affected versions <= 2.0.17) contains a remote code execution…. This entry ships a detection-only PoC and a Docker test lab.


CVE	CVE-2026-85604
Severity	High (8.8)
Detection / prevention	—
PoC	poc.py
Source	2026/CVE-2026-85604/

Details¶

English | 한국어

Description¶

Grav before 2.0.19 (affected versions <= 2.0.17) contains a remote code execution vulnerability in the Twig sort filter. The sortFunc wrapper in GravExtension.php hardcodes Twig's isSandboxed argument to false, so unlike |map/|filter/|reduce, |sort accepts a plain function name inside the sandbox; the remaining denylist misses spl_autoload, which performs a PHP include. An authenticated user with only page-write rights (admin.pages or api.pages.write) can supply a crafted payload (e.g., via form frontmatter rendered by the Email plugin) that invokes spl_autoload through the sort filter, resulting in arbitrary PHP execution as the web server user.

Vulnerability Details¶

Property	Value
CVE ID	CVE-2026-85604
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-2026-85604/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-2026-85604

# 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/getgrav/grav/security/advisories/GHSA-p6qj-p5m7-f62h
https://www.vulncheck.com/advisories/grav-before-2.0.19-remote-code-execution-via-sort-filter

Generated by PoC Generator on 2026-09-04T22:55:56.151939445

Frequently asked questions¶

What is CVE-2026-85604?¶

CVE-2026-85604 is a High (8.8) vulnerability: Grav before 2.0.19 (affected versions <= 2.0.17) contains a remote code execution…. This entry ships a detection-only PoC and a Docker test lab.

How do I detect CVE-2026-85604?¶

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-2026-85604?¶

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.