{"id":"CVE-2026-45315","aliases":["GHSA-m8f9-9whg-f4xr","PYSEC-2026-2748"],"url":"https://o3.security/vulnerability/CVE-2026-45315","summary":"Open WebUI: Stored XSS via attacker-controlled file extension in /api/v1/audio/transcriptions","details":"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.","published":"2026-05-15T21:26:54.790Z","modified":"2026-08-12T03:51:40.318395195Z","cvss":{"score":8.7,"severity":"HIGH","vector":"CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:H/I:H/A:N"},"epss":{"score":0.00186,"percentile":0.08415,"asOf":"2026-08-09"},"cisaKev":null,"exploitsKnown":0,"affectedPackages":[{"ecosystem":"PyPI","name":"open-webui","fixedVersion":"0.9.3"}],"fix":null,"references":[{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/45xxx/CVE-2026-45315.json"},{"type":"ADVISORY","url":"https://github.com/open-webui/open-webui/security/advisories/GHSA-m8f9-9whg-f4xr"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-45315"}],"provenance":{"sources":["OSV.dev","FIRST.org (EPSS)"],"lastVerified":"2026-08-12T03:51:40.318395195Z"}}