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

Exp

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: 2026-05-15 Last update: 2026-05-19 Assigner: [email protected] Source: [email protected]
NVD Status：Modified，CVE State: published
View at NVD, CVE.org, EUVD

CVE-2026-45315 is rated Exploit Available (52.6/100): CVSS High severity, with low exploitation likelihood (EPSS 0.18%). 1 public exploit reference(s) are indexed (Exploit-DB). Public exploits are available—assess exposure, apply mitigations, and prioritize patching.

Risk is dynamic; we continuously reassess and refresh what is shown on this page as upstream context changes.

Public exploit references (Exploit-DB) for CVE-2026-45315

EDB-ID Source Kind Published Link
— nvd_ref exploit_tag Exploit-DB ↗

Exploit prediction scoring system (EPSS) score for CVE-2026-45315

EPSS lead: Daily EPSS estimates relative likelihood of exploitation; percentile ranks this CVE among scored vulnerabilities (higher = more severe relative rank).

# Date Old EPSS score New EPSS score Delta (New - Old)
1 2026-06-15 0.02% 0.18% +0.16%
2 2026-05-16 — 0.02% —

Full EPSS history (2 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2026-45315

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
8.7 3.1 HIGH
CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:H/I:H/A:N Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:L)
Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:L)
A normal user session is enough; they don’t have to be admin.
User interaction (UI:R)
A real person has to do something—click, install, enable—otherwise it doesn’t land.
Scope (S:C)
Breaking this can reach past the original component and bite other resources—bigger blast radius.
Confidentiality (C:H)
Serious risk that confidential data gets exposed in a big way.
Integrity (I:H)
They could widely tamper with or forge data—trust in the data is badly hurt.
Availability (A:N)
Service keeps running; no real outage angle.
 2.3 5.8 [email protected]

Weakness enumeration for CVE-2026-45315

GitHub Security Advisory for CVE-2026-45315

GHSA-m8f9-9whg-f4xr · Severity: high · Ecosystem: pip — Open WebUI has stored XSS via attacker-controlled file extension in /api/v1/audio/transcriptions

Affected software / configurations for CVE-2026-45315

Vendor Product Version Raw CPE
openwebui open_webui < 0.9.3 cpe:2.3:a:openwebui:open_webui:*:*:*:*:*:*:*:*

References for CVE-2026-45315

cvelogic Threat Intelligence