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TI-2026-32467 Aliases CVE-2026-44555GHSA-9vvh-qmjx-p4q8

Open WebUI: Base Model Routing Bypasses Access Control via Model Chaining

Priority HIGH 66CWE-862Published · Updated

Key facts

Attack vector
Network
Privileges required
Low
User interaction
None
Attack complexity
Low
Impact type
Security bypass
Confidentiality · integrity · availability
High · Low · Low
Fix status
Fixed

Attack profile from CVSS 3.1 · CNA. Fix status from CNA and GitHub. Impact type from CWE-862.

Summary

Open WebUI is a self-hosted artificial intelligence platform designed to operate entirely offline. Prior to 0.9.0, Open WebUI supports model composition via base_model_id: a user-defined model (e.g., "Cheap Assistant") can reference an existing base model (e.g., "gpt-4-turbo-restricted") that provides the actual inference capability. When a user queries the composed model, the access control pipeline verifies the user has access to the composed model but never re-verifies access to the chained base model. Additionally, the model creation and import endpoints accept arbitrary base_model_id values without checking that the caller has access to that base model. Combined, this allows any user with the default model creation permission to create a model that chains to a restricted base model — and then invoke it, causing the server to dispatch the request to the restricted base model using the admin-configured API key. This vulnerability is fixed in 0.9.0.

Why it matters now

Exploitation Proof of concept CISA SSVC · not in CISA KEV
EPSS 0.00304 23rd percentileScored 2026-11-07
Public exploit Yes 1 exploit referenceTagged by NVD
Fix Fixed open-webui (open-webui): 0.9.0open-webui (PyPI): 0.9.0

SSVC decision points

CISA ADP · SSVC 2.0.3

Exploitation
Poc
Automatable
No
Technical impact
Partial

The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.

Affected products

VendorProductAffected versionsFixed inStatusSource
open-webuiopen-webuibefore 0.9.00.9.0Patch availableCNA
—open-webui (PyPI)before 0.9.00.9.0Patch availableGHSA-9vvh-qmjx-p4q8
  • open-webui Vendoropen-webui Affected before 0.9.0 Fixed in 0.9.0 Patch available CNA
  • open-webui (PyPI) Vendor— Affected before 0.9.0 Fixed in 0.9.0 Patch available GHSA-9vvh-qmjx-p4q8

CPE configurations NVD · 1

CPEVersionsRoleVendor
cpe:2.3:a:openwebui:open_webui:*:*:*:*:*:*:*:*before 0.9.0Vulnerableopen-webui
  • cpe:2.3:a:openwebui:open_webui:*:*:*:*:*:*:*:* Versions before 0.9.0 Vulnerable ·open-webui

Remediation

  • Fix · CNA open-webui (open-webui) Fixed in 0.9.0
  • Fix · GHSA-9vvh-qmjx-p4q8 open-webui (PyPI) Fixed in 0.9.0 Advisory →

Timeline

  1. 2026-10-02 Threatist record created from CVE-2026-44555
  2. 2026-10-03 Alias added: GHSA-9vvh-qmjx-p4q8

References

Exploit 1

Advisory 1

Other 1

  • TI-2024-06216 Open WebUI Arbitrary File Upload + Path Traversal CVSS 3.1HIGH 8.8
  • TI-2024-07467 Improper Authentication in open-webui/open-webui CVSS 3.1HIGH 8.2
  • TI-2026-42359 Open WebUI: Cross-user code-interpreter and tool execution via unvalidated Socket.IO event-caller session_id CVSS 3.1CRITICAL 9.0
  • TI-2026-40759 open-webui - Remote Code Execution via CORS Misconfiguration and Session Validation CVSS 4.0CRITICAL 9.0
  • TI-2024-07431 Cross-site Scripting (XSS) in open-webui/open-webui CVSS 3.0CRITICAL 9.0
  • TI-2026-60021 Open WebUI: Same-origin XSS to account takeover via terminal port-preview iframe hardcoding allow-same-origin CVSS 3.1HIGH 8.7
See all 154 →

Sources

This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences