CVE-2026-81849 — Improper limitation of a pathname to a restricted directory in the aws:downloadContent…¶

Key facts

CVE-2026-81849 is a High (8.8) vulnerability: Improper limitation of a pathname to a restricted directory in the aws:downloadContent…. This entry ships a detection-only PoC and a Docker test lab.


CVE	CVE-2026-81849
Severity	High (8.8)
Detection / prevention	—
PoC	poc.py
Source	2026/CVE-2026-81849/

Details¶

English | 한국어

Description¶

Improper limitation of a pathname to a restricted directory in the aws:downloadContent plugin in amazon-ssm-agent before 3.3.4515.0 might allow an authenticated remote user whose ssm:SendCommand permission is restricted to the AWS-DownloadContent document, to write arbitrary files outside the intended download directory with root privileges, via crafted object keys in the S3 source the document is directed to retrieve. This issue may lead to arbitrary code execution as root if specific sensitive files are overwritten.

To remediate this issue, customers should upgrade amazon-ssm-agent to version 3.3.4515.0 or later.

Vulnerability Details¶

Property	Value
CVE ID	CVE-2026-81849
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-2026-81849/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-2026-81849

# 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://aws.amazon.com/security/security-bulletins/2026-091-aws/
https://github.com/aws/amazon-ssm-agent/releases/tag/3.3.4515.0

Generated by PoC Generator on 2026-08-29T21:38:42.22699452

Frequently asked questions¶

What is CVE-2026-81849?¶

CVE-2026-81849 is a High (8.8) vulnerability: Improper limitation of a pathname to a restricted directory in the aws:downloadContent…. This entry ships a detection-only PoC and a Docker test lab.

How do I detect CVE-2026-81849?¶

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-2026-81849?¶

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.