CVE-2026-44556 — Open WebUI: responses passthrough endpoint lacks access control authorization

Description (CNA)

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.

Affected (CNA)

Vendor / product	Versions
open-webui / open-webui	affected < 0.9.0

CWE

CWE-284, CWE-862

References

https://github.com/open-webui/open-webui/security/advisories/GHSA-hp5m-24vp-vq2q

ADP enrichment

CISA-ADP

No English description supplied.

No references supplied.