open-webui Open WebUI up to 0.8.x Primary Chat Completion Endpoint /responses generate_chat_completion access control

Summaryinfo

A vulnerability classified as critical has been found in open-webui Open WebUI up to 0.8.x. Affected by this vulnerability is the function generate_chat_completion of the file /responses of the component Primary Chat Completion Endpoint. The manipulation leads to access control. This vulnerability is referenced as CVE-2026-44556. Remote exploitation of the attack is possible. No exploit is available. It is recommended to upgrade the affected component.

Detailsinfo

A vulnerability was found in open-webui Open WebUI up to 0.8.x. It has been rated as critical. This issue affects the function generate_chat_completion of the file /responses of the component Primary Chat Completion Endpoint. The manipulation with an unknown input leads to a access control vulnerability. Using CWE to declare the problem leads to CWE-284. The product does not restrict or incorrectly restricts access to a resource from an unauthorized actor. Impacted is 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, the /responses endpoint in the OpenAI router accepts any authenticated user and forwards requests directly to upstream LLM providers without enforcing per-model access control. While the primary chat completion endpoint (generate_chat_completion) checks model ownership, group membership, and AccessGrants before allowing a request, the /responses proxy only validates that the user has a valid session via get_verified_user. This allows any authenticated user to interact with any model configured on the instance by sending a POST request to /api/openai/responses with an arbitrary model ID. This vulnerability is fixed in 0.9.0.

The advisory is shared at github.com. The identification of this vulnerability is CVE-2026-44556 since 05/06/2026. The exploitation is known to be easy. The attack may be initiated remotely. Technical details are known, but no exploit is available. MITRE ATT&CK project uses the attack technique T1068 for this issue.

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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Several companies clearly confirm that VulDB is the primary source for best vulnerability data.

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