Open WebUI has Broken Access Control for Completions API

Exploitation

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

CVSS

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

EPSS

• CVE-2026-45349: 0.23% estimated exploitation activity in the next 30 days; percentile 14.11 (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 Any user X can continue the conversation of any other user Y, as long as the Chat ID of Y is known. User X does not even need to be an admin to do so. Details A user just needs to use the API endpoint: /api/chat/completions with their own API key (generated in OWUI) and the Chat ID of another user. OWUI does not check to match the Chat ID with the user that created that Chat ID. Note that both users will need access to the same model. This is especially relevant if there is a shared pipeline model between users. PoC 1. Using OWUI v0.6.18 2. Sign in with any user X 3. Generate an API Key for user X using the settings 4. Create another user Y, and have a conversation in OWUI. Copy the Chat ID from the URL. 5. User X can now use the API /api/chat/completions and the Chat ID from step 4 to continue the conversation of user Y Impact Large impact to any user in OWUI. People can read your conversations, and access private information if they know your Chat ID (which is in the URL of…

Published by the source

14 May 2026, 20:24 UTC

Last modified by the source

13 Jul 2026, 16:42 UTC

Source last checked

26 Oct 2026, 13:41 UTC

1. Revision 2 · amended · 26 Oct 2026

   Amended from ghsa record GHSA-gfm2-xm6c-37qc

2. Revision 1 · created · 24 Oct 2026

   Published from osv record GHSA-gfm2-xm6c-37qc

Preview the exact text before you copy it. Commands are read-only suggestions; review them before running anything.

# Patch Next advisory brief: CVE-2026-45349

Advisory: Open WebUI has Broken Access Control for Completions API
IDs: CVE-2026-45349, GHSA-gfm2-xm6c-37qc
Record: https://patchnext.com/advisories/cve-2026-45349 (revision 2, source checked 26 Oct 2026, 13:41 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: High (CVSS 7.1)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: open-webui 0.9.0. A vendor fix does not mean a deployment is fixed.

## Affected components
- PyPI open-webui: affected <= 0.8.12; fixed in 0.9.0

## 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-gfm2-xm6c-37qc (OSV record GHSA-gfm2-xm6c-37qc lists affected ranges: PyPI open-webui >=0 <0.9.0 (fixed))
- Verified: https://github.com/advisories/GHSA-gfm2-xm6c-37qc (GitHub-reviewed advisory GHSA-gfm2-xm6c-37qc lists affected ranges: PyPI open-webui >=0 <=0.8.12)

Commands are suggestions: review each one before running it.