{"id":"CVE-2026-44556","state":"PUBLISHED","title":"Open WebUI: responses passthrough endpoint lacks access control authorization","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.","publishedAt":"2026-05-15T19:46:17.750Z","updatedAt":"2026-05-15T22:21:46.573Z","severity":{"score":7.1,"label":"High","version":"3.1","vector":"CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:H","source":"GitHub_M"},"assigner":"GitHub_M","products":["open-webui open-webui"],"affected":[{"vendor":"open-webui","product":"open-webui","versions":[{"version":"< 0.9.0","status":"affected"}]}],"references":["https://github.com/open-webui/open-webui/security/advisories/GHSA-hp5m-24vp-vq2q"],"weaknesses":["CWE-284","CWE-862"],"ingestedAt":"2026-10-29T20:11:57.932Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/44xxx/CVE-2026-44556.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-44556","state":"PUBLISHED","datePublished":"2026-05-15T19:46:17.750Z","dateUpdated":"2026-05-15T22:21:46.573Z","assignerShortName":"GitHub_M","assignerOrgId":"a0819718-46f1-4df5-94e2-005712e83aaa","dateReserved":"2026-05-06T20:59:00.594Z"},"containers":{"cna":{"title":"Open WebUI: responses passthrough endpoint lacks access control authorization","descriptions":[{"lang":"en","value":"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":[{"vendor":"open-webui","product":"open-webui","versions":[{"version":"< 0.9.0","status":"affected"}]}],"references":[{"url":"https://github.com/open-webui/open-webui/security/advisories/GHSA-hp5m-24vp-vq2q","name":"https://github.com/open-webui/open-webui/security/advisories/GHSA-hp5m-24vp-vq2q","tags":["x_refsource_CONFIRM"]}],"metrics":[{"cvssV3_1":{"attackComplexity":"LOW","attackVector":"NETWORK","availabilityImpact":"HIGH","baseScore":7.1,"baseSeverity":"HIGH","confidentialityImpact":"LOW","integrityImpact":"NONE","privilegesRequired":"LOW","scope":"UNCHANGED","userInteraction":"NONE","vectorString":"CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:H","version":"3.1"}}],"problemTypes":[{"descriptions":[{"cweId":"CWE-284","lang":"en","description":"CWE-284: Improper Access Control","type":"CWE"}]},{"descriptions":[{"cweId":"CWE-862","lang":"en","description":"CWE-862: Missing Authorization","type":"CWE"}]}],"providerMetadata":{"shortName":"GitHub_M","orgId":"a0819718-46f1-4df5-94e2-005712e83aaa","dateUpdated":"2026-05-15T19:46:17.750Z"},"source":{"advisory":"GHSA-hp5m-24vp-vq2q","discovery":"UNKNOWN"}},"adp":[{"title":"CISA ADP Vulnrichment","metrics":[{"other":{"type":"ssvc","content":{"timestamp":"2026-05-15T22:15:01.153605Z","id":"CVE-2026-44556","options":[{"Exploitation":"none"},{"Automatable":"no"},{"Technical Impact":"partial"}],"role":"CISA Coordinator","version":"2.0.3"}}}],"providerMetadata":{"shortName":"CISA-ADP","orgId":"134c704f-9b21-4f2e-91b3-4a467353bcc0","dateUpdated":"2026-05-15T22:21:46.573Z"}}]}}}