Open WebUI: Stored XSS via attacker-controlled file extension in /api/v1/audio/transcriptions_CVE-2026-45315

{
    "lastseen": "",
    "description": "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 \u2014 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": "2026-05-15T21:26:54.790Z",
    "type": "cve",
    "title": "Open WebUI: Stored XSS via attacker-controlled file extension in /api/v1/audio/transcriptions",
    "source": "GitHub_M",
    "references": "https://github.com/open-webui/open-webui/security/advisories/GHSA-m8f9-9whg-f4xr",
    "id": "CVE-2026-45315",
    "bulletinFamily": "",
    "cwe": [
        "CWE-79",
        "CWE-434",
        "CWE-646"
    ],
    "cvelist": null,
    "sourceData": "open-webui open-webui < 0.9.3",
    "sourceHref": "",
    "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",
        "version": "3.1"
    },
    "cvss2": [],
    "cvss3": {
        "version": "",
        "vectorString": "",
        "baseScore": 0,
        "baseSeverity": "",
        "attackVector": "",
        "attackComplexity": "",
        "privilegesRequired": "",
        "userInteraction": "",
        "scope": "",
        "confidentialityImpact": "",
        "integrityImpact": "",
        "availabilityImpact": "",
        "cvssV3": {
            "version": "",
            "vectorString": "",
            "baseScore": 0,
            "baseSeverity": "",
            "attackVector": "",
            "attackComplexity": "",
            "privilegesRequired": "",
            "userInteraction": "",
            "scope": "",
            "confidentialityImpact": "",
            "integrityImpact": "",
            "availabilityImpact": ""
        }
    },
    "href": "",
    "category_name": "CVE",
    "post_link": "",
    "product": "open-webui",
    "version": "< 0.9.3",
    "vendor": "open-webui",
    "ai_description": "Stored XSS via attacker-controlled file extension in audio transcription upload endpoint",
    "ai_severity": "High",
    "ai_vendor": "Open WebUI",
    "ai_product": "Open WebUI",
    "ai_version": "< 0.9.3",
    "ai_score": 8.7
}