Overly permissive cross-domain whitelist in Open WebUI - CVE-2026-56400
Published: May 5, 2026 / Updated: September 14, 2026
Vulnerability identifier: #VU130181
CSH Severity: Medium
CVSS v4: 6.3 [CVSS:4.0/AV:N/AC:H/AT:N/PR:N/UI:N/VC:L/VI:L/VA:N/SC:N/SI:N/SA:N]
CVE-ID: CVE-2026-56400
CWE-ID: CWE-942
Exploitation vector: Remote access
Exploit availability:
No public exploit available
Vulnerability details
The vulnerability allows a remote attacker to bypass the CORS protection mechanism.
The vulnerability exists due to incorrect processing of the "Origin" HTTP header that is supplied within HTTP request and allow_credentials=True. A remote attacker can supply arbitrary value via the "Origin" HTTP header, bypass implemented CORS protection mechanism and perform cross-site scripting attacks against the vulnerable application.
Affected software
Open WebUI
How to mitigate CVE-2026-56400
Install updates from vendor's website.
Open WebUI - update to 0.3.33