{"id":"CVE-2026-59822","aliases":["GHSA-7488-6r32-c95q","PYSEC-2026-3479"],"url":"https://o3.security/vulnerability/CVE-2026-59822","summary":"LiteLLM: MCP Authentication Bypass via OAuth2 Passthrough Fallback","details":"LiteLLM is a proxy server (AI Gateway) to call LLM APIs in OpenAI (or native) format. Prior to 1.84.0, LiteLLM's MCP Streamable HTTP endpoint allowed an unauthenticated attacker to use a fabricated Authorization header to trigger an OAuth2 passthrough fallback path that replaced failed LiteLLM key validation with an empty UserAPIKeyAuth() object, allowing requests to reach MCP tooling without a valid LiteLLM key. This issue is fixed in version 1.84.0.","published":"2026-07-08T19:32:18.611Z","modified":"2026-08-12T03:51:12.662655499Z","cvss":null,"epss":null,"cisaKev":null,"exploitsKnown":0,"affectedPackages":[{"ecosystem":"PyPI","name":"litellm","fixedVersion":"1.84.0"}],"fix":{"url":"https://github.com/BerriAI/litellm/commit/73869f0faf7d11ee21adcb5f91b8c33a340b6c2c","label":"BerriAI/litellm@73869f0"},"references":[{"type":"WEB","url":"https://github.com/BerriAI/litellm/releases/tag/v1.84.0"},{"type":"ADVISORY","url":"https://github.com/BerriAI/litellm/security/advisories/GHSA-7488-6r32-c95q"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/59xxx/CVE-2026-59822.json"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-59822"},{"type":"FIX","url":"https://github.com/BerriAI/litellm/commit/73869f0faf7d11ee21adcb5f91b8c33a340b6c2c"},{"type":"FIX","url":"https://github.com/BerriAI/litellm/pull/26463"}],"provenance":{"sources":["OSV.dev","FIRST.org (EPSS)"],"lastVerified":"2026-08-12T03:51:12.662655499Z"}}