CVE-2026-28786: Openwebui Open Webui

Medium severity, CVSS 4.3. EPSS: 0.4% chance of exploitation in the next 30 days.

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.

Affected products

• Openwebui Open Webui: before 0.8.6 (fixed in 0.8.6)

Published 2026-03-27. Last modified 2026-06-17.