Authorization bypass through user-controlled key in Open WebUI - CVE-2026-54009
Published: June 30, 2026
Vulnerability identifier: #VU135945
CSH Severity: Low
CVSS v4.0: CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N/E:U/U:Clear
CVE-ID: CVE-2026-54009
CWE-ID: CWE-639
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 disclose sensitive information.
The vulnerability exists due to improper access control in the convert_url_images_to_base64 image_url file resolution path when processing chat completion requests with a non-http image_url.url value treated as a file id. A remote user can submit a crafted chat completion request referencing another user's file id to disclose sensitive information.
Exploitation requires a valid file id and is limited to content that the LLM accepts through the image_url attachment flow.
How to mitigate CVE-2026-54009
Install security update from vendor's website.