{
  "affected": [
    {
      "ranges": [
        {
          "database_specific": {
            "extracted_events": [
              {
                "range": [
                  {
                    "introduced": "1.8.0"
                  },
                  {
                    "fixed": "1.30.0"
                  }
                ],
                "source": "AFFECTED_FIELD",
                "strategy": "StringRangeExpression"
              },
              {
                "range": [
                  {
                    "introduced": "2.0.0"
                  },
                  {
                    "fixed": "2.2.0"
                  }
                ],
                "source": "AFFECTED_FIELD",
                "strategy": "StringRangeExpression"
              },
              {
                "range": [
                  {
                    "fixed": "2106335745563b2321b8c73fef2c12903d00aa6e"
                  }
                ],
                "source": "REFERENCES_COMMIT"
              },
              {
                "range": [
                  {
                    "fixed": "c6762e821c527925f0b617db216d00fbd1d0bf99"
                  }
                ],
                "source": "REFERENCES_COMMIT"
              },
              {
                "original_tag": "v1.30.0",
                "range": [
                  {
                    "fixed": "8c2fa6eabacde869d75568e33b9d466b58c2f512"
                  }
                ],
                "source": "REFERENCES_TAG"
              },
              {
                "original_tag": "v2.2.0",
                "range": [
                  {
                    "fixed": "9972c21aa42054fb1450c5fc614761ed11847ec6"
                  }
                ],
                "source": "REFERENCES_TAG"
              }
            ]
          },
          "events": [
            {
              "introduced": "ed25167fa5d715733437996682e20c24470e8177"
            },
            {
              "fixed": "8c2fa6eabacde869d75568e33b9d466b58c2f512"
            },
            {
              "introduced": "6f69a3758ebf2ee55ce050f58b470ce11af71133"
            },
            {
              "fixed": "9972c21aa42054fb1450c5fc614761ed11847ec6"
            },
            {
              "fixed": "2106335745563b2321b8c73fef2c12903d00aa6e"
            },
            {
              "fixed": "c6762e821c527925f0b617db216d00fbd1d0bf99"
            }
          ],
          "repo": "https://github.com/modelcontextprotocol/python-sdk",
          "type": "GIT"
        }
      ]
    }
  ],
  "aliases": [
    "GHSA-5h93-6whr-6q8j"
  ],
  "database_specific": {
    "cna_assigner": "GitHub_M",
    "cwe_ids": [
      "CWE-200"
    ],
    "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/116xxx/CVE-2026-116685.json"
  },
  "details": "The Model Context Protocol Python SDK is the official Python SDK for Model Context Protocol servers and clients. From 1.8.0 until 1.30.0 and 2.2.0, streamable_http_client, streamablehttp_client, sse_client, ClientSessionGroup, OAuth, and create_mcp_http_client client paths enable follow_redirects and follow redirects to a different origin, forwarding caller-supplied custom credential headers and, for 307 or 308 responses, the request body. An attacker who can influence a trusted endpoint's redirect destination can receive that material. This issue is fixed in versions 1.30.0 and 2.2.0.",
  "id": "CVE-2026-116685",
  "modified": "2026-10-29T02:30:39.769900485Z",
  "published": "2026-10-27T19:26:46.926Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/modelcontextprotocol/python-sdk/releases/tag/v1.30.0"
    },
    {
      "type": "WEB",
      "url": "https://github.com/modelcontextprotocol/python-sdk/releases/tag/v2.2.0"
    },
    {
      "type": "ADVISORY",
      "url": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/116xxx/CVE-2026-116685.json"
    },
    {
      "type": "ADVISORY",
      "url": "https://github.com/modelcontextprotocol/python-sdk/security/advisories/GHSA-5h93-6whr-6q8j"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-116685"
    },
    {
      "type": "FIX",
      "url": "https://github.com/modelcontextprotocol/python-sdk/commit/2106335745563b2321b8c73fef2c12903d00aa6e"
    },
    {
      "type": "FIX",
      "url": "https://github.com/modelcontextprotocol/python-sdk/commit/c6762e821c527925f0b617db216d00fbd1d0bf99"
    },
    {
      "type": "FIX",
      "url": "https://github.com/modelcontextprotocol/python-sdk/pull/3397"
    },
    {
      "type": "FIX",
      "url": "https://github.com/modelcontextprotocol/python-sdk/pull/3448"
    }
  ],
  "schema_version": "1.9.2",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N",
      "type": "CVSS_V3"
    }
  ],
  "summary": "Model Context Protocol Python SDK: HTTP client transports followed cross-origin redirects carrying custom headers and bodies"
}