Open WebUI — Info Disclosure (CVE-2026-28786)
Date: 2026-03
Affected: openwebui/open_webui
Attack vector: info-disclosure
Category: vulnerability-disclosure
Severity: Medium
CVE: CVE-2026-28786
CWE: CWE-209
CWE-22
CVSS: 4.3 (CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:N)

Open WebUI is a self-hosted artificial intelligence platform designed to operate entirely offline. Prior to version 0.8.6, an unsanitized filename field in the speech-to-text transcription endpoint allows any authenticated non-admin user to trigger a `FileNotFoundError` whose message — including the server's absolute `DATA_DIR` path — is returned verbatim in the HTTP 400 response body, confirming information disclosure on all default deployments. Version 0.8.6 patches the issue.


Mitigations:

Architectural layers (MAESTRO):