Open WebUI vulnerable to Path Traversal in POST /api/v1/audio/transcriptions

Exploitation

No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.

CVSS

4.3 · CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:N

EPSS

• CVE-2026-28786: 0.57% estimated exploitation activity in the next 30 days; percentile 47.31 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.

As published by the source; long descriptions are shortened.

Summary An unsanitised filename field in the speech-to-text transcription endpoint allows any authenticated non-admin user to trigger a FileNotFoundError whose message — including the server's absolute DATADIR path — is returned verbatim in the HTTP 400 response body, confirming information disclosure on all default deployments. Details backend/openwebui/routers/audio.py:1197 extracts a file extension from the raw multipart filename using file.filename.split(".")[-1] with no path sanitisation. The result is concatenated into a filesystem path and passed to open(): If the filename is audio./etc/passwd, split(".")[-1] yields /etc/passwd and the assembled path becomes: open() fails with FileNotFoundError. The outer except block at line 1231 returns the exception via ERRORMESSAGES.DEFAULT(e), leaking the full absolute path in the response body. The MIME-type guard at line 1190 checks Content-Type (a separate multipart field) and does not constrain filename. Setting Content-Type:…

Published by the source

27 Mar 2026, 15:29 UTC

Last modified by the source

13 Jul 2026, 16:43 UTC

Source last checked

26 Oct 2026, 13:37 UTC

1. Revision 2 · amended · 26 Oct 2026

   Amended from ghsa record GHSA-vvxm-vxmr-624h

2. Revision 1 · created · 24 Oct 2026

   Published from osv record GHSA-vvxm-vxmr-624h

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# Patch Next advisory brief: CVE-2026-28786

Advisory: Open WebUI vulnerable to Path Traversal in `POST /api/v1/audio/transcriptions`
IDs: CVE-2026-28786, GHSA-vvxm-vxmr-624h
Record: https://patchnext.com/advisories/cve-2026-28786 (revision 2, source checked 26 Oct 2026, 13:37 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: Medium (CVSS 4.3)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: open-webui 0.8.6. A vendor fix does not mean a deployment is fixed.

## Affected components
- PyPI open-webui: affected < 0.8.6; fixed in 0.8.6

## Suggested inspection (read-only)
- `python -m pip show open-webui`: prints the installed version. Run with the environment that serves production active.

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on open-webui.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://osv.dev/vulnerability/GHSA-vvxm-vxmr-624h (OSV record GHSA-vvxm-vxmr-624h lists affected ranges: PyPI open-webui >=0 <0.8.6 (fixed))
- Verified: https://github.com/advisories/GHSA-vvxm-vxmr-624h (GitHub-reviewed advisory GHSA-vvxm-vxmr-624h lists affected ranges: PyPI open-webui >=0 <0.8.6)

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