CVE-2026-45387: Open WebUI Sharing Models For Others To Vulnerability

MODERATE
Advisory Identifier: GHSA-h2cw-7qw9-56xr
Share
CVSS 4.3
CWE-200
Published
Advisory Summary

CVE-2026-45387 is a MODERATE (CVSS 4.3) sharing models for others to vulnerability (CWE-200: Exposure of Sensitive Information to an Unauthorized Actor) affecting Open WebUI libraries in the PyPI ecosystem. The issue involves sharing models for others to use (read permission) also exposes model details (system prompt leakage). Remediation is available by upgrading affected packages to version 0.9.5.

CVE-2026-45387 at a Glance

CVE Identifier CVE-2026-45387
GHSA Identifier GHSA-h2cw-7qw9-56xr
Severity MODERATE
CVSS v3.1 Base Score 4.3
CWE Classification CWE-200: Exposure of Sensitive Information to an Unauthorized Actor
Affected Product Open WebUI
Package Ecosystem PyPI
Published Date
Last Updated

Security Impact

CVSS: 4.3

The security impact metrics below are parsed directly from the CVSS v3.1 vector string (CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:N).

Attack Vector Network (AV:N)
Attack Complexity Low (AC:L)
Privileges Required Low (PR:L)
User Interaction None (UI:N)
Scope Unchanged (S:U)
Confidentiality Low (C:L)
Integrity None (I:N)
Availability None (A:N)

How to Fix CVE-2026-45387

To remediate this vulnerability, upgrade all affected Open WebUI dependencies to a patched release. Both direct and transitive dependencies should be checked, as frameworks or security libraries may pull in vulnerable versions transitively.

open-webui fixed: 0.9.5 
pip install open-webui>=0.9.5
Verify Direct and Transitive Dependencies

Run the following command in your project directory to verify that all resolved dependencies use the patched release: 

pip show open-webui

How to Check if You Are Affected

To determine whether your Python environment is affected by CVE-2026-45387, inspect your installed packages using pip:

pip show open-webui

Analyze the terminal output to locate any version of Open WebUI in your dependency tree. If any resolved version matches the vulnerable ranges listed in the table below (for example, versions earlier than 0.9.5), your application is affected.

Note: The pip show open-webui command checks currently installed packages in your active Python environment.

Technical Details

Vulnerability Mechanism & Technical Analysis

This vulnerability is classified under CWE-200: Exposure of Sensitive Information to an Unauthorized Actor, where the product exposes sensitive information to an actor that is not explicitly authorized to have access to that information. In Open WebUI, software state validation or input boundaries are circumvented during processing. Review the official source advisory statement below for specific affected components, classes, and reproduction details.

Source Advisory Statement

### 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: - ```/api/v1/models/model?id=notmymodel``` -> returns the model details, most importantly params.system - even though ```/api/v1/models/list``` does NOT contain the model since it checks for write permission. - ```/api/models``` 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 - create model - give read permission to group with another user - other user can access ```/api/v1/models/model?id=notmymodel``` ### Impact System prommpt leakage If this is intended behavior for the "read" permission, maybe there should be an additional "use" permission (which would be 99% of use cases of the read permission i believe).

CVE-2026-45387 Affected Open WebUI Versions

1 component(s)
Fixed Versions:
0.9.5
Product / Package Ecosystem Affected Versions Fixed Version
open-webui
pypi/open-webui
PyPI
< 0.9.5
0.9.5

References

GitHub Advisory / Wiki ADVISORY
https://github.com/open-webui/open-webui/security/advisories/GHSA-h2cw-7qw9-56xr
NVD — CVE-2026-45387 NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-45387
Open WebUI Source Repository REPOSITORY
https://github.com/open-webui/open-webui
Open WebUI Release RELEASE
https://github.com/open-webui/open-webui/releases/tag/v0.9.5

Frequently Asked Questions

What is CVE-2026-45387?
CVE-2026-45387 is a security vulnerability in Open WebUI involving Sharing models for others to use (read permission) also exposes model details (system prompt leakage) under CWE-200: Exposure of Sensitive Information to an Unauthorized Actor.
Which Open WebUI versions are affected?
Affected versions include releases prior to 0.9.5 across affected packages: open-webui.
What version fixes CVE-2026-45387?
Upgrading to 0.9.5 (or the latest patched release for your respective branch) resolves the vulnerability.
Is open-webui affected?
Yes, open-webui is affected in releases prior to 0.9.5. Upgrade your dependency to 0.9.5 or later.
What is the CVSS score of CVE-2026-45387?
CVE-2026-45387 has a CVSS v3.1 base score of 4.3 (MODERATE) with vector string CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:N.
What CWE is associated with CVE-2026-45387?
CVE-2026-45387 is classified under CWE-200: Exposure of Sensitive Information to an Unauthorized Actor (The product exposes sensitive information to an actor that is not explicitly authorized to have access to that information.).
How can I check PyPI dependencies for CVE-2026-45387?
Run the dependency tree command: 'pip show open-webui'. This command lists direct and transitive dependencies in your build configuration so you can verify if a vulnerable version is resolved.
Machine-readable OSV JSON OSV v1.5 Schema
Normalized schema output
View Raw JSON 
{
  "schema_version" : "1.4.0",
  "id" : "GHSA-h2cw-7qw9-56xr",
  "modified" : "2026-05-15T23:54:25Z",
  "published" : "2026-05-14T20:26:03Z",
  "aliases" : [ "CVE-2026-45387" ],
  "summary" : "Open WebUI: Sharing models for others to use (read permission) also exposes model details (system prompt leakage)",
  "details" : "### Summary\nWhen 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.\n\nHowever users may consider their system prompt confidential, so we consider this a security issue.\n\nCompare https://genai.owasp.org/llmrisk/llm072025-system-prompt-leakage/ or prompt injections to get popular chatbots on the internet to reveal their prompt.\n\n### Details\n\nWe discovered that users can open the workspace model edit page /workspace/models/edit?id=notmymodel for models that do not appear in their workspace.\n\nSaving is not possible, that permission check is correct.\n\nOn the API level:\n\n- ```/api/v1/models/model?id=notmymodel``` -> returns the model details, most importantly params.system\n- even though ```/api/v1/models/list``` does NOT contain the model since it checks for write permission.\n- ```/api/models``` contains the model correctly and does not reveal the system prompt.\n\nIt seems inconsistent that the REST API list does not contain an item, but if you know the id, you can access it anyway.\n\n### PoC\n- create model\n- give read permission to group with another user\n- other user can access ```/api/v1/models/model?id=notmymodel```\n\n### Impact\nSystem prommpt leakage\n\nIf this is intended behavior for the \"read\" permission, maybe there should be an additional \"use\" permission (which would be 99% of use cases of the read permission i believe).",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:N"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "PyPI",
      "name" : "open-webui"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0"
      }, {
        "fixed" : "0.9.5"
      } ]
    } ],
    "database_specific" : {
      "last_known_affected_version_range" : "<= 0.9.4"
    }
  } ],
  "references" : [ {
    "type" : "WEB",
    "url" : "https://github.com/open-webui/open-webui/security/advisories/GHSA-h2cw-7qw9-56xr"
  }, {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2026-45387"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/open-webui/open-webui"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/open-webui/open-webui/releases/tag/v0.9.5"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-200" ],
    "severity" : "MODERATE",
    "github_reviewed" : true,
    "github_reviewed_at" : "2026-05-14T20:26:03Z",
    "nvd_published_at" : "2026-05-15T21:16:37Z"
  }
}