CVE-2026-45315: Openwebui Open Webui

High severity, CVSS 8.7. EPSS: 0.2% chance of exploitation in the next 30 days.

Open WebUI is a self-hosted artificial intelligence platform designed to operate entirely offline. Prior to 0.9.3, the audio transcription upload endpoint takes the file extension from the user-supplied filename and saves the file under CACHE_DIR/audio/transcriptions/.. The /cache/{path} route serves these files via FileResponse, which sets Content-Type from the on-disk extension and emits no Content-Disposition. A verified user with the default-on chat.stt permission can upload a polyglot WAV+HTML file named pwn.html and trick any other user into opening the resulting URL — the response comes back as text/html and any embedded <script> runs in the Open WebUI origin. This vulnerability is fixed in 0.9.3.

Affected products

• Openwebui Open Webui: before 0.9.3 (fixed in 0.9.3)

Published 2026-05-15. Last modified 2026-06-17.