What’s Vulnerable › Vulnerabilities
CVE-2026-44556: Open WebUI: responses passthrough endpoint lacks access control authorization
- Severity: high (CVSS 7.1 v3.1)
- Exploited in the wild: not listed in CISA KEV
- EPSS: 0.3% probability of exploitation in the next 30 days
- Public exploit or detection template: none known
- Published: 2026-05-15 · updated 2026-06-17
- Weakness: CWE-284
Description
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 products
- open-webui: before 0.9.0 — fixed in 0.9.0
How to fix
Upgrade to a fixed version: open-webui 0.9.0. Check the vendor advisory for mitigations.
References
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