CVE-2026-0767: Open WebUI Information Disclosure Flaw

CVE-2026-0767 Overview

CVE-2026-0767 is a cleartext transmission of credentials vulnerability affecting Open WebUI installations. This information disclosure vulnerability allows network-adjacent attackers to intercept and disclose sensitive credential information without requiring authentication. The flaw exists within the handling of credentials provided to the endpoint, where sensitive authentication data is transmitted in plaintext rather than through secure encrypted channels.

Critical Impact

Network-adjacent attackers can intercept transmitted credentials in cleartext, potentially leading to unauthorized access and further system compromise.

Affected Products

• Open WebUI (all versions prior to patch)

Discovery Timeline

• 2026-01-23 - CVE CVE-2026-0767 published to NVD
• 2026-01-26 - Last updated in NVD database

Technical Details for CVE-2026-0767

Vulnerability Analysis

This vulnerability is classified under CWE-319 (Cleartext Transmission of Sensitive Information). The flaw resides in how Open WebUI handles credential transmission to its endpoints. When users authenticate or submit credentials through the affected interface, the application fails to enforce encrypted communication channels, resulting in sensitive authentication data being transmitted in plaintext across the network.

The network-adjacent attack vector means that an attacker must be positioned on the same network segment as either the victim or the vulnerable Open WebUI server to successfully intercept traffic. This could include scenarios such as shared corporate networks, public Wi-Fi environments, or compromised network infrastructure. The vulnerability requires high attack complexity due to the specific positioning requirements, but once achieved, no authentication or user interaction is needed to exploit it.

Root Cause

The root cause of this vulnerability stems from improper implementation of transport layer security for credential handling endpoints. The application fails to enforce HTTPS or other secure transport mechanisms when processing authentication credentials, allowing sensitive data to traverse the network in cleartext format. This represents a fundamental security design oversight that violates secure coding practices for credential management.

Attack Vector

An attacker positioned on the same network segment can leverage network sniffing techniques to capture plaintext credentials as they are transmitted between the client and the Open WebUI server. Common attack scenarios include:

1. Passive Network Monitoring: Using tools like Wireshark or tcpdump to capture network traffic containing cleartext credentials
2. ARP Spoofing: Poisoning the ARP cache to redirect traffic through the attacker's machine for interception
3. Man-in-the-Middle Positioning: Exploiting network infrastructure weaknesses to position between the client and server

The intercepted credentials can then be used for unauthorized access to user accounts, privilege escalation, or lateral movement within the target environment. This vulnerability was tracked by the Zero Day Initiative as ZDI-CAN-28259.

Detection Methods for CVE-2026-0767

Indicators of Compromise

• Unusual network traffic patterns involving unencrypted HTTP connections to Open WebUI authentication endpoints
• Evidence of ARP spoofing or network interception attacks on segments hosting Open WebUI
• Unauthorized account access or credential reuse attacks following deployment of affected Open WebUI versions
• Network captures showing credentials transmitted in plaintext format

Detection Strategies

• Deploy network intrusion detection systems (NIDS) to monitor for cleartext credential transmission patterns
• Implement TLS inspection at network boundaries to identify applications sending credentials over unencrypted channels
• Review Open WebUI access logs for suspicious authentication patterns or access from unexpected network locations
• Utilize SentinelOne's network visibility capabilities to detect anomalous traffic patterns associated with credential interception

Monitoring Recommendations

• Enable comprehensive network logging on segments hosting Open WebUI deployments
• Configure alerting for any HTTP (non-HTTPS) traffic to authentication endpoints
• Monitor for indicators of ARP spoofing or other network-layer attacks in environments running Open WebUI
• Implement continuous credential monitoring to detect compromised account usage

How to Mitigate CVE-2026-0767

Immediate Actions Required

• Enforce HTTPS/TLS for all Open WebUI communications immediately
• Deploy reverse proxy configurations with mandatory TLS termination in front of Open WebUI instances
• Segment network access to Open WebUI servers to limit exposure to potential network-adjacent attackers
• Conduct credential rotation for any accounts that may have been exposed through cleartext transmission

Patch Information

Refer to the Zero Day Initiative Advisory ZDI-26-033 for the latest patch information and remediation guidance from the vendor. Organizations should monitor Open WebUI release channels for security updates addressing this vulnerability.

Workarounds

• Configure a reverse proxy (nginx, Apache, or similar) with TLS termination to encrypt all traffic to Open WebUI
• Implement network segmentation to isolate Open WebUI servers from untrusted network segments
• Deploy VPN or other encrypted tunnel solutions for users accessing Open WebUI from potentially compromised networks
• Enable HTTP Strict Transport Security (HSTS) headers through reverse proxy configuration

# Example nginx reverse proxy configuration with TLS enforcement
server {
    listen 443 ssl;
    server_name openwebui.example.com;
    
    ssl_certificate /etc/ssl/certs/openwebui.crt;
    ssl_certificate_key /etc/ssl/private/openwebui.key;
    ssl_protocols TLSv1.2 TLSv1.3;
    ssl_ciphers HIGH:!aNULL:!MD5;
    
    # Enforce HTTPS with HSTS
    add_header Strict-Transport-Security "max-age=31536000; includeSubDomains" always;
    
    location / {
        proxy_pass http://localhost:8080;
        proxy_set_header Host $host;
        proxy_set_header X-Real-IP $remote_addr;
        proxy_set_header X-Forwarded-Proto https;
    }
}

# Redirect HTTP to HTTPS
server {
    listen 80;
    server_name openwebui.example.com;
    return 301 https://$server_name$request_uri;
}