A critical security flaw has been found in Open-WebUI, an open-source web interface for large language models. This vulnerability, identified as CVE-2026-56400, could allow attackers to remotely execute malicious code on affected systems. The issue stems from a misconfiguration in how Open-WebUI handles cross-origin requests and problems with how user sessions are managed. Essentially, a specially crafted malicious website could trick an authenticated administrator into executing commands on their Open-WebUI instance with just one click. Since Open-WebUI often runs with high privileges in its default Docker setup, this could lead to a complete takeover of the affected container.
CVE Details
- Product Name: Open-WebUI
- Published Date: July 15, 2026
- Severity: HIGH (CVSS 8.3)
- Status: Analyzed
Affected Products
This vulnerability impacts Open-WebUI versions prior to 0.3.33. If you are running an older version, your system could be at risk.
Current Status
The vulnerability has been analyzed, and a fix is available. Users are strongly encouraged to update their Open-WebUI instances to a patched version to protect against potential exploitation.
Severity Level
CVE-2026-56400 is rated as HIGH severity with a CVSS score of 8.3. This high rating reflects the significant danger posed by the vulnerability. An attacker can exploit this remotely over a network, and while it requires some user interaction (an administrator clicking a malicious link), the impact on confidentiality, integrity, and availability is severe, potentially leading to a complete compromise of the system where Open-WebUI is running.
Possible Solutions
The most crucial step to mitigate this vulnerability is to update your Open-WebUI installation to version 0.3.33 or later. This patched version addresses both the CORS misconfiguration and the session validation issues.
Additionally, it is recommended to review your Open-WebUI’s CORS settings. Avoid using broad allow_origins settings like “*” or “*.com”. Instead, configure specific, trusted origins. For enhanced security, ensure that user sessions are properly invalidated and cleared upon logout. Each new session should generate new cookies, and old session cookies should be removed from the browser’s storage after a user logs out.
References
https://github.com/open-webui/open-webui/security/advisories/GHSA-6xcp-7mpr-m7wm
https://www.vulncheck.com/advisories/open-webui-remote-code-execution-via-cors-misconfiguration-and-session-validation
