open-webui Open WebUI up to 0.8.x base_model_id authorization

Summaryinfo

A vulnerability marked as critical has been reported in open-webui Open WebUI up to 0.8.x. This impacts the function base_model_id. Performing a manipulation results in authorization. This vulnerability was named CVE-2026-44555. The attack may be initiated remotely. There is no available exploit. It is suggested to upgrade the affected component.

Detailsinfo

A vulnerability was found in open-webui Open WebUI up to 0.8.x. It has been classified as critical. This affects the function base_model_id. The manipulation with an unknown input leads to a authorization vulnerability. CWE is classifying the issue as CWE-862. The product does not perform an authorization check when an actor attempts to access a resource or perform an action. This is going to have an impact on confidentiality, integrity, and availability. The summary by CVE is:

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.

It is possible to read the advisory at github.com. This vulnerability is uniquely identified as CVE-2026-44555 since 05/06/2026. The exploitability is told to be easy. It is possible to initiate the attack remotely. Technical details of the vulnerability are known, but there is no available exploit.

Upgrading to version 0.9.0 eliminates this vulnerability.

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Productinfo

Vendor

• open-webui

Name

• Open WebUI

Version

• 0.1
• 0.2
• 0.3
• 0.4
• 0.5
• 0.6
• 0.7
• 0.8

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CPE 2.2info

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