XSS in Open-Webui
CVE-2026-45315
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.
Vulnerability class: XSS (Cross-Site Scripting)
EPSS: 0.002 (8.3th percentile) — read the EPSS interpretation.
CVSS v3 metric
CVSS v3 base score 8.7 (High). Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:H/I:H/A:N.
Affected products
- Open-webui — versions < 0.9.3
- Openwebui Open_webui
Weakness classification (CWE)
References
- security-advisories@github.com (x_refsource_CONFIRM, Exploit, Mitigation, Vendor Advisory)
Frequently asked questions
- What is CVE-2026-45315?
- CVE-2026-45315 is a high-severity vulnerability in Open-Webui, classified under Cross-site Scripting. CVSS score: 8.7/10. Published 2026-05-15.
- How severe is CVE-2026-45315?
- High severity. CVSS v3 base score is 8.7 out of 10.