CVE-2026-44556
Published: 15 May 2026
Summary
CVE-2026-44556 is a high-severity Improper Access Control (CWE-284) vulnerability in Openwebui Open Webui. Its CVSS base score is 7.1 (High).
Operationally, exploitation aligns with the MITRE ATT&CK technique Exploit Public-Facing Application (T1190); ranked at the 2.6th percentile by exploit likelihood (below the median); it is not currently listed in the CISA KEV catalog.
This vulnerability is AI-related — categorised as LLM Application Platforms; in the LLM/Generative AI Risks risk domain.
EU & UK References
- 🇪🇺 ENISA EUVD: EUVD-2026-30624
Vulnerability details
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.…
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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.
- CWE(s)
AI Security AnalysisAI
- AI Category
- LLM Application Platforms
- Risk Domain
- LLM/Generative AI Risks
- OWASP Top 10 for LLMs 2025
- None mapped
- Classification Reason
- Matched keywords: artificial intelligence, llm, open webui, openai
Related Threats
MITRE ATT&CK Enterprise TechniquesAI
Why these techniques?
Missing authorization check on /responses API endpoint directly enables exploitation of the public/self-hosted web application to access restricted models.
CVEs Like This One
Affected Assets
Mitigating Controls
Likely Mitigating Controls AI
Per-CVE control mapping for this CVE has not run yet; the list below is derived from the weakness types (CWEs) cited in the NVD entry.
The access control policy and procedures directly mandate and enforce proper access control mechanisms across the organization.
Supervision and review of access control activities directly detects and remediates improper access configurations or usages.
Explicitly identifying and documenting actions permitted without identification or authentication enforces proper access control boundaries by defining justified exceptions.
Associating and retaining security attributes with data directly supports enforcement of access control decisions across storage, processing, and transmission.
Requiring prior authorization for each remote access type prevents improper access control over remote connections.
Requiring authorization of wireless access before allowing connections enforces proper access control for this access method.
Requiring authorization and configuration controls for mobile device connections directly enforces access control and prevents unauthorized devices from reaching organizational systems.
Defining account types, requiring approvals for creation, specifying authorizations, monitoring usage, and reviewing accounts directly prevents improper access control by ensuring only authorized accounts exist and are used.