CVE-2026-39362: InvenTree SSRF Vulnerability

CVE-2026-39362 Overview

CVE-2026-39362 is a Server-Side Request Forgery (SSRF) vulnerability affecting InvenTree, an Open Source Inventory Management System. When the INVENTREE_DOWNLOAD_FROM_URL feature is enabled (opt-in), authenticated users can exploit insufficient URL validation to make the server perform arbitrary HTTP requests to internal resources and private networks.

Critical Impact

Authenticated attackers can bypass URL validation checks to access internal services, potentially exposing sensitive internal infrastructure, cloud metadata endpoints, and private network resources.

Affected Products

• InvenTree versions prior to 1.2.7
• InvenTree versions prior to 1.3.0

Discovery Timeline

• 2026-04-08 - CVE CVE-2026-39362 published to NVD
• 2026-04-08 - Last updated in NVD database

Technical Details for CVE-2026-39362

Vulnerability Analysis

This vulnerability falls under CWE-918 (Server-Side Request Forgery). The flaw exists in InvenTree's image download functionality, which allows authenticated users to specify remote URLs for fetching images. The server-side implementation uses Python's requests.get() to fetch the specified URL with only Django's URLValidator performing basic URL format validation.

The core security issue is the absence of validation against private IP ranges (such as 10.0.0.0/8, 172.16.0.0/12, 192.168.0.0/16) or internal hostnames. This means an attacker can craft URLs pointing to internal services that would otherwise be inaccessible from outside the network perimeter.

Root Cause

The root cause of this vulnerability is insufficient server-side URL validation in the remote_image parameter handling. While Django's URLValidator ensures the URL is syntactically correct, it does not perform security-critical checks such as:

1. Blocking requests to private/internal IP address ranges
2. Preventing resolution of internal DNS hostnames
3. Validating the final destination after HTTP redirects

Additionally, the requests.get() call is configured with allow_redirects=True, which enables attackers to bypass even basic URL-format restrictions by using open redirects or URL shorteners to ultimately reach internal targets.

Attack Vector

The attack requires network access and authenticated user privileges. An attacker with valid credentials can submit crafted remote_image URLs through the image download feature. The attack flow involves:

1. Authenticating to the InvenTree application with valid credentials
2. Identifying endpoints that accept remote_image URLs when INVENTREE_DOWNLOAD_FROM_URL is enabled
3. Submitting URLs targeting internal services (e.g., http://169.254.169.254/latest/meta-data/ for cloud metadata)
4. Leveraging HTTP redirects to bypass any URL format restrictions
5. Exfiltrating responses or probing internal network topology

The vulnerability is particularly concerning in cloud environments where metadata endpoints can leak sensitive credentials and configuration data.

Detection Methods for CVE-2026-39362

Indicators of Compromise

• Unusual outbound HTTP requests from the InvenTree server to internal IP ranges (10.x.x.x, 172.16.x.x-172.31.x.x, 192.168.x.x)
• HTTP requests to cloud metadata endpoints (e.g., 169.254.169.254)
• Unexpected DNS queries for internal hostnames originating from the web application server
• Access logs showing remote_image parameters with internal or localhost URLs

Detection Strategies

• Monitor web application logs for remote_image URL parameters containing private IP addresses or internal hostnames
• Implement network-level monitoring for outbound connections from application servers to internal subnets
• Configure alerts for requests to known cloud metadata IP addresses from application tier
• Review authentication logs for users frequently submitting remote image URLs

Monitoring Recommendations

• Deploy network segmentation to isolate the InvenTree application server from sensitive internal resources
• Implement egress filtering to restrict outbound connections from the application server
• Configure web application firewall (WAF) rules to detect SSRF patterns in request parameters
• Enable detailed logging for all URL fetching operations in the application

How to Mitigate CVE-2026-39362

Immediate Actions Required

• Upgrade InvenTree to version 1.2.7 or 1.3.0 immediately
• If unable to upgrade, disable the INVENTREE_DOWNLOAD_FROM_URL feature by setting it to False
• Audit logs for evidence of exploitation attempts targeting internal resources
• Review network access controls and implement egress filtering for the application server

Patch Information

The vulnerability has been fixed in InvenTree versions 1.2.7 and 1.3.0. Organizations should upgrade to one of these patched versions as soon as possible. For additional details and patch information, refer to the GitHub Security Advisory.

Workarounds

• Disable the INVENTREE_DOWNLOAD_FROM_URL feature if remote image fetching is not required for your deployment
• Implement network-level restrictions to prevent the InvenTree server from accessing internal resources or cloud metadata endpoints
• Deploy a proxy layer for all outbound HTTP requests that validates and filters destination URLs
• Use network segmentation to isolate the InvenTree deployment from sensitive internal services

# Configuration example - Disable remote URL downloading
# In your InvenTree configuration file or environment variables:
INVENTREE_DOWNLOAD_FROM_URL=False

# Or configure network egress rules to block internal ranges
# Example iptables rule to block metadata endpoint
iptables -A OUTPUT -d 169.254.169.254 -j DROP