CVE-2026-0765: Open WebUI Command Injection RCE Flaw

CVE-2026-0765 Overview

CVE-2026-0765 is a command injection vulnerability affecting Open WebUI that enables remote code execution through the install_frontmatter_requirements function. This vulnerability allows authenticated remote attackers to execute arbitrary code on affected installations by exploiting improper validation of user-supplied input before it is used in system calls.

The flaw stems from insufficient sanitization of user-controlled strings that are passed to system-level command execution, allowing attackers to inject malicious commands that execute in the context of the service account running Open WebUI.

Critical Impact

Authenticated attackers can achieve full remote code execution on the underlying server, potentially compromising sensitive data, pivoting to internal networks, or establishing persistent access to the affected system.

Affected Products

• Open WebUI (all versions prior to patch)

Discovery Timeline

• 2026-01-23 - CVE-2026-0765 published to NVD
• 2026-01-26 - Last updated in NVD database

Technical Details for CVE-2026-0765

Vulnerability Analysis

This command injection vulnerability (CWE-78) exists within the install_frontmatter_requirements function of Open WebUI. The function processes user-supplied input to install Python package dependencies but fails to properly validate or sanitize the input before passing it to a system call. This allows an authenticated attacker to craft malicious input that breaks out of the intended command context and executes arbitrary system commands.

The vulnerability requires authentication to exploit, meaning an attacker must first obtain valid credentials or session access to the Open WebUI application. Once authenticated, the attacker can leverage this flaw to execute code with the same privileges as the service account running the Open WebUI instance.

Root Cause

The root cause of this vulnerability is the lack of proper input validation and sanitization in the install_frontmatter_requirements function. User-supplied strings are directly incorporated into system calls without adequate escaping or validation, enabling command injection attacks. This violates secure coding practices that require all external input to be treated as untrusted and properly sanitized before use in security-sensitive operations such as shell command execution.

Attack Vector

The attack is network-based and requires low attack complexity once authentication is obtained. An authenticated attacker can submit a specially crafted request containing malicious command injection payloads to the vulnerable function. The payload would typically include shell metacharacters (such as ;, |, &&, or backticks) followed by arbitrary commands.

For example, an attacker could inject commands to establish reverse shells, download and execute malicious payloads, exfiltrate sensitive data, or modify system configurations. The commands execute with the privileges of the Open WebUI service account, which may have elevated permissions depending on the deployment configuration.

For detailed technical information about this vulnerability, refer to the Zero Day Initiative Advisory ZDI-26-031.

Detection Methods for CVE-2026-0765

Indicators of Compromise

• Unusual process spawning from the Open WebUI service process, particularly shell interpreters like /bin/sh, /bin/bash, or cmd.exe
• Network connections originating from the Open WebUI server to unexpected external IP addresses
• Suspicious entries in application logs containing shell metacharacters or encoded payloads in package requirement fields
• Unexpected files created in temporary directories or web-accessible paths by the service account

Detection Strategies

• Monitor process execution chains for the Open WebUI service, alerting on child processes that indicate command execution (shells, scripting interpreters, network utilities)
• Implement web application firewall (WAF) rules to detect command injection patterns in HTTP request parameters
• Deploy endpoint detection and response (EDR) solutions like SentinelOne to identify and block anomalous behavior patterns indicative of post-exploitation activity
• Review application logs for requests to endpoints associated with the install_frontmatter_requirements functionality

Monitoring Recommendations

• Enable verbose logging for the Open WebUI application to capture all requests to package installation functionality
• Configure SIEM alerts for command injection indicators in web application logs
• Monitor outbound network traffic from the Open WebUI server for signs of data exfiltration or command-and-control communication
• Implement file integrity monitoring on critical system directories accessible by the service account

How to Mitigate CVE-2026-0765

Immediate Actions Required

• Restrict network access to Open WebUI installations to trusted users and networks only
• Review and audit user accounts with access to the Open WebUI application, removing unnecessary privileges
• Implement network segmentation to limit the blast radius of potential compromise
• Deploy SentinelOne agents on systems running Open WebUI to detect and block exploitation attempts

Patch Information

Consult the Zero Day Initiative Advisory ZDI-26-031 for the latest patch information and vendor remediation guidance. Apply security updates from the Open WebUI project as soon as they become available.

Workarounds

• Disable or restrict access to the package installation functionality if not required for operations
• Implement additional authentication controls or IP-based access restrictions for administrative functions
• Deploy a reverse proxy with strict input validation rules in front of the Open WebUI application
• Run the Open WebUI service with minimal privileges using a dedicated service account with restricted system access

# Example: Restrict Open WebUI service permissions
# Create dedicated service account with minimal privileges
useradd -r -s /sbin/nologin openwebui-svc

# Ensure the service runs as the restricted user
# Update systemd service file or container configuration accordingly
chown -R openwebui-svc:openwebui-svc /opt/openwebui
chmod 750 /opt/openwebui