Authentication Bypass by Spoofing in Open WebUI - #VU136848
Published: July 3, 2026
Vulnerability identifier: #VU136848
CSH Severity: Medium
CVSS v4.0: CVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:A/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:U/U:Green
CVE-ID: N/A
CWE-ID: CWE-290
Exploitation vector: Remote access
Exploit availability:
No public exploit available
Vendor: Open WebUI
Affected software:
Open WebUI
Open WebUI
Detailed vulnerability description
The vulnerability allows a remote user to spoof another user's identity to access that user's terminal scope.
The vulnerability exists due to authentication bypass by spoofing in the terminal proxy in backend/open_webui/routers/terminals.py when forwarding terminal identity to the upstream terminal server or backend coordinator. A remote user can supply crafted terminal requests or a crafted session_id value to make the upstream resolve a spoofed user identity and access that user's terminal scope.
On the WebSocket path, exploitation can allow attaching to a live PTY when a valid active session ID is known, such as one exposed through a shared chat.
Remediation
Install security update from vendor's website.