Open WebUI: Sharing models for others to use (read permission) also exposes model details (system prompt leakage)

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-2026-45387: 0.22% estimated exploitation activity in the next 30 days; percentile 12.58 (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 When setting model permissions so that a group has read access to it, intending for other users to use it, those users also can read the model's system prompt. However users may consider their system prompt confidential, so we consider this a security issue. Compare https://genai.owasp.org/llmrisk/llm072025-system-prompt-leakage/ or prompt injections to get popular chatbots on the internet to reveal their prompt. Details We discovered that users can open the workspace model edit page /workspace/models/edit?id=notmymodel for models that do not appear in their workspace. Saving is not possible, that permission check is correct. On the API level: - - returns the model details, most importantly params.system - even though does NOT contain the model since it checks for write permission. - contains the model correctly and does not reveal the system prompt. It seems inconsistent that the REST API list does not contain an item, but if you know the id, you can access it anyway. PoC -…

Published by the source

14 May 2026, 20:26 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-h2cw-7qw9-56xr

2. Revision 1 · created · 24 Oct 2026

   Published from osv record GHSA-h2cw-7qw9-56xr

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# Patch Next advisory brief: CVE-2026-45387

Advisory: Open WebUI: Sharing models for others to use (read permission) also exposes model details (system prompt leakage)
IDs: CVE-2026-45387, GHSA-h2cw-7qw9-56xr
Record: https://patchnext.com/advisories/cve-2026-45387 (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: 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 0.9.5. A vendor fix does not mean a deployment is fixed.

## Affected components
- PyPI open-webui: affected <= 0.9.4; fixed in 0.9.5

## 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-h2cw-7qw9-56xr (OSV record GHSA-h2cw-7qw9-56xr lists affected ranges: PyPI open-webui >=0 <0.9.5 (fixed))
- Verified: https://github.com/advisories/GHSA-h2cw-7qw9-56xr (GitHub-reviewed advisory GHSA-h2cw-7qw9-56xr lists affected ranges: PyPI open-webui >=0 <=0.9.4)

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