CVE-2026-34225: Open WebUI Blind SSRF Vulnerability

CVE-2026-34225 Overview

CVE-2026-34225 is a Blind Server-Side Request Forgery (SSRF) vulnerability affecting Open WebUI, a self-hosted artificial intelligence platform designed to operate entirely offline. The vulnerability exists in the image editing functionality that allows users to modify images via prompts. By exploiting this flaw, an authenticated attacker can perform unauthorized GET requests to arbitrary URLs, including internal network addresses, enabling reconnaissance of the local network infrastructure.

Critical Impact

Attackers can perform internal network port scanning and potentially interact with internal services that expose state-changing GET request endpoints, compromising network security and enabling further attacks against internal infrastructure.

Affected Products

• Open WebUI versions 0.7.2 and below

Discovery Timeline

• 2026-04-14 - CVE-2026-34225 published to NVD
• 2026-04-14 - Last updated in NVD database

Technical Details for CVE-2026-34225

Vulnerability Analysis

This vulnerability is classified as CWE-918 (Server-Side Request Forgery). The affected functionality in Open WebUI performs a GET request to a user-provided URL without implementing any domain restrictions or validation. Since the platform is designed to operate offline and within local environments, this lack of input validation allows attackers to target the local address space, including internal services that would otherwise be inaccessible from external networks.

The SSRF vulnerability is categorized as "blind" because the attacker cannot directly read the response content from the internal requests. However, the attacker can still infer information based on response differentials—specifically, whether the GET request succeeds or fails. This timing and error-based information leakage enables effective port scanning of the internal network.

Root Cause

The root cause of this vulnerability is improper input validation in the image editing prompt functionality. The application accepts user-supplied URLs and performs HTTP GET requests without implementing allowlisting, blocklisting, or any other form of URL validation. The absence of restrictions on which domains or IP addresses can be accessed allows requests to internal network resources, localhost services, and cloud metadata endpoints.

Attack Vector

The attack requires network access and low-privilege authentication to the Open WebUI platform. An attacker can exploit this vulnerability through the following methodology:

1. The attacker authenticates to the Open WebUI platform with a valid user account
2. The attacker accesses the image editing functionality that accepts URL parameters
3. The attacker supplies a URL pointing to an internal IP address and port (e.g., http://192.168.1.1:22/, http://127.0.0.1:3306/)
4. The server performs the GET request on behalf of the attacker
5. Based on the response time or error messages, the attacker determines if the port is open
6. The attacker automates this process to enumerate all ports on target internal hosts

If an internal service running on an open port accepts state-changing GET requests (contrary to REST best practices), the attacker may be able to trigger unintended actions on that service.

Detection Methods for CVE-2026-34225

Indicators of Compromise

• Unusual outbound HTTP GET requests from the Open WebUI server to internal IP ranges (e.g., 10.0.0.0/8, 172.16.0.0/12, 192.168.0.0/16)
• Rapid sequential requests to the same internal host on different ports indicative of port scanning activity
• GET requests targeting localhost addresses (127.0.0.1, ::1) or cloud metadata endpoints (169.254.169.254)
• Abnormal volume of requests from a single authenticated user to the image editing functionality

Detection Strategies

• Implement network traffic monitoring to detect outbound connections from the Open WebUI server to internal IP ranges
• Configure web application firewalls (WAF) to alert on SSRF patterns in URL parameters
• Enable verbose logging on the Open WebUI application to capture all URL parameters submitted to the image editing functionality
• Deploy endpoint detection solutions to identify port scanning patterns originating from the application server

Monitoring Recommendations

• Monitor application logs for repeated failed or successful requests to internal addresses
• Set up alerts for any requests to RFC 1918 private address ranges or link-local addresses
• Review authentication logs for users making excessive requests to the image editing feature
• Implement network segmentation monitoring to detect unauthorized cross-segment communication attempts

How to Mitigate CVE-2026-34225

Immediate Actions Required

• Restrict network egress from the Open WebUI server to only required external services using firewall rules
• Implement network segmentation to isolate the Open WebUI server from sensitive internal resources
• Review and audit user accounts with access to the image editing functionality
• Consider disabling the image editing via URL feature if not business-critical until a patch is available

Patch Information

This vulnerability was unresolved at the time of publication. No official patch is currently available from the vendor. Organizations should monitor the GitHub Security Advisory for updates on patch availability. When a fix is released, upgrade beyond version 0.7.2 immediately.

Workarounds

• Deploy a reverse proxy or web application firewall (WAF) in front of Open WebUI to filter and block requests containing internal IP addresses or localhost references
• Implement strict egress filtering on the network level to prevent the Open WebUI server from initiating connections to internal services
• Use network policies (if running in Kubernetes or similar container orchestration) to restrict pod-to-pod communication
• Apply URL allowlisting at the application or proxy layer to only permit requests to known, trusted external domains

# Example: iptables egress filtering to block requests to internal networks
# Block requests to private IP ranges from the Open WebUI server
iptables -A OUTPUT -d 10.0.0.0/8 -j DROP
iptables -A OUTPUT -d 172.16.0.0/12 -j DROP
iptables -A OUTPUT -d 192.168.0.0/16 -j DROP
iptables -A OUTPUT -d 127.0.0.0/8 -j DROP
iptables -A OUTPUT -d 169.254.169.254 -j DROP