CVE-2026-0766: Open WebUI Command Injection RCE Flaw

CVE-2026-0766 Overview

CVE-2026-0766 is a critical command injection vulnerability discovered in Open WebUI that enables authenticated remote attackers to execute arbitrary code on affected installations. The vulnerability resides in the load_tool_module_by_id function, which fails to properly validate user-supplied input before using it to execute Python code. This flaw allows attackers who have obtained valid credentials to leverage the vulnerability to execute code in the context of the service account, potentially leading to complete system compromise.

Critical Impact

Authenticated attackers can achieve remote code execution by injecting malicious Python code through the load_tool_module_by_id function, potentially compromising the entire Open WebUI installation and underlying server infrastructure.

Affected Products

• Open WebUI (specific versions not disclosed)

Discovery Timeline

• 2026-01-23 - CVE-2026-0766 published to NVD
• 2026-01-26 - Last updated in NVD database

Technical Details for CVE-2026-0766

Vulnerability Analysis

This vulnerability is classified as CWE-94 (Improper Control of Generation of Code - Code Injection). The flaw exists within the load_tool_module_by_id function in Open WebUI, which is responsible for dynamically loading tool modules based on user-specified identifiers. The function accepts user-controlled input and uses it to construct and execute Python code without adequate sanitization or validation.

The vulnerability is network-exploitable with low attack complexity, requiring only low-level authenticated privileges. No user interaction is needed beyond the initial authentication. Successful exploitation results in complete compromise of confidentiality, integrity, and availability of the affected system, as the attacker gains code execution capabilities within the service account context.

Root Cause

The root cause of this vulnerability is insufficient input validation in the load_tool_module_by_id function. The function accepts a tool module identifier from authenticated users and uses this value to dynamically generate and execute Python code. Without proper sanitization, an attacker can inject malicious Python statements that execute alongside the intended module loading logic. This is a classic code injection pattern where user input is directly incorporated into executable code.

Attack Vector

The attack vector leverages the network-accessible load_tool_module_by_id function in Open WebUI. An attacker must first authenticate to the application using valid credentials. Once authenticated, the attacker can craft a malicious tool module identifier containing Python code injection payloads. When the application processes this request, the injected code is executed in the context of the service account running Open WebUI.

The vulnerability mechanism involves the application's failure to distinguish between legitimate module identifiers and malicious input containing Python syntax. Attackers can inject arbitrary Python statements, enabling them to execute system commands, access sensitive data, establish persistence, or pivot to other systems on the network. For detailed technical information, refer to the Zero Day Initiative Advisory ZDI-26-032.

Detection Methods for CVE-2026-0766

Indicators of Compromise

• Unusual or malformed requests to the load_tool_module_by_id endpoint containing Python syntax or special characters
• Unexpected child processes spawned by the Open WebUI service account
• Anomalous outbound network connections from the Open WebUI server
• Log entries showing module loading failures followed by successful arbitrary code execution patterns

Detection Strategies

• Implement web application firewall (WAF) rules to detect and block requests containing Python code injection patterns targeting the load_tool_module_by_id function
• Deploy endpoint detection and response (EDR) solutions to monitor for suspicious process execution chains originating from the Open WebUI service
• Enable detailed application logging and monitor for requests with unusual characters or Python keywords in module identifier parameters
• Utilize network intrusion detection systems (NIDS) to identify anomalous traffic patterns associated with post-exploitation activities

Monitoring Recommendations

• Monitor Open WebUI application logs for authentication events followed by suspicious module loading requests
• Implement file integrity monitoring on the Open WebUI installation directory to detect unauthorized modifications
• Configure alerting for any command execution or shell spawning from the Open WebUI service account
• Establish baseline behavior patterns for the Open WebUI service and alert on deviations

How to Mitigate CVE-2026-0766

Immediate Actions Required

• Restrict network access to Open WebUI installations to trusted IP ranges only
• Audit all user accounts with access to Open WebUI and disable unnecessary accounts
• Implement additional authentication controls such as multi-factor authentication to reduce the risk of credential compromise
• Deploy web application firewall rules to filter requests containing code injection patterns

Patch Information

At the time of publication, no vendor patch information is available in the public CVE data. Organizations should monitor the Zero Day Initiative Advisory ZDI-26-032 for updates on remediation guidance and coordinate with Open WebUI maintainers for patch availability.

Workarounds

• Restrict access to the vulnerable load_tool_module_by_id functionality through application-level access controls or by disabling the feature if not required
• Implement network segmentation to isolate Open WebUI servers from critical infrastructure
• Deploy application-layer filtering to validate and sanitize input to the vulnerable function before processing
• Consider running Open WebUI in a containerized or sandboxed environment to limit the impact of potential exploitation

# Example: Restrict network access to Open WebUI using iptables
# Allow access only from trusted management network
iptables -A INPUT -p tcp --dport 8080 -s 10.0.0.0/24 -j ACCEPT
iptables -A INPUT -p tcp --dport 8080 -j DROP