CVE-2026-0766 in Open WebUI
Summary
by MITRE • 01/23/2026
Open WebUI load_tool_module_by_id Command Injection Remote Code Execution Vulnerability. This vulnerability allows remote attackers to execute arbitrary code on affected installations of Open WebUI. Authentication is required to exploit this vulnerability.
The specific flaw exists within the load_tool_module_by_id function. The issue results from the lack of proper validation of a user-supplied string before using it to execute Python code. An attacker can leverage this vulnerability to execute code in the context of the service account. Was ZDI-CAN-28257.
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Analysis
by VulDB Data Team • 01/25/2026
The CVE-2026-0766 vulnerability represents a critical command injection flaw within the Open WebUI application that enables remote code execution when proper authentication is bypassed. This vulnerability specifically targets the load_tool_module_by_id function, which serves as a critical component in the application's tool management system. The flaw stems from inadequate input validation mechanisms that fail to properly sanitize user-supplied data before it is processed within the Python execution context. When an authenticated attacker successfully exploits this vulnerability, they can inject malicious commands that will be executed with the privileges of the service account running the Open WebUI application. The vulnerability's classification as a command injection issue aligns with CWE-77 and CWE-94, which specifically address improper validation of input used in command execution and code injection attacks respectively. This weakness creates a significant attack surface that allows adversaries to escalate their privileges and potentially gain full control over the affected system.
The technical implementation of this vulnerability occurs when the load_tool_module_by_id function processes user-provided identifiers without adequate sanitization or validation. The application fails to implement proper input filtering or escaping mechanisms before passing the user-supplied data to Python's execution functions. This creates an environment where an attacker can craft malicious payloads that, when processed by the vulnerable function, result in arbitrary code execution. The vulnerability's impact is particularly severe because it operates within the context of the service account, which typically has elevated privileges and access to system resources. The attack vector requires authentication, meaning that unauthorized users cannot directly exploit the vulnerability, but legitimate users with access can leverage this flaw for privilege escalation or lateral movement within the network. This authentication requirement does not mitigate the severity of the vulnerability, as it still allows for code execution within the application's execution context.
The operational impact of CVE-2026-0766 extends beyond simple code execution to potentially compromise the entire Open WebUI infrastructure. When an attacker successfully exploits this vulnerability, they can execute commands with the same privileges as the service account, which may include access to sensitive data, system files, and network resources. The vulnerability's presence in the tool module loading functionality means that attackers can potentially load and execute malicious modules that could persist across system restarts or be used to establish backdoors. This type of vulnerability falls under ATT&CK technique T1059 which covers command and scripting interpreter, and T1068 which covers exploit for privilege escalation. The attack surface is further expanded by the fact that this vulnerability can be leveraged to perform reconnaissance activities, data exfiltration, or to establish persistence mechanisms within the target environment. The ZDI-CAN-28257 reference indicates that this vulnerability has been formally recognized by the Zero Day Initiative, highlighting its significance in the cybersecurity community.
Mitigation strategies for CVE-2026-0766 must address both immediate remediation and long-term security hardening measures. The primary recommendation involves implementing proper input validation and sanitization for all user-supplied data that is processed within the load_tool_module_by_id function. This includes validating data types, implementing strict parameter validation, and ensuring that all user input is properly escaped before being used in any execution context. Organizations should also consider implementing least privilege principles for the service account running Open WebUI, limiting the potential impact of successful exploitation. Additional security measures include regular security updates and patches, implementing network segmentation to limit access to the Open WebUI application, and establishing monitoring and detection capabilities to identify suspicious activities. The vulnerability's characteristics make it particularly susceptible to automated exploitation, so organizations should also implement web application firewalls and intrusion detection systems to prevent unauthorized access attempts. Regular security assessments and penetration testing should be conducted to identify similar vulnerabilities within the application's codebase and ensure that proper security controls are in place to prevent future exploitation attempts.