{
  "affected": [
    {
      "ranges": [
        {
          "database_specific": {
            "versions": [
              {
                "introduced": "0"
              },
              {
                "fixed": "1.4.1"
              }
            ]
          },
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "580f2a09be5c5b7ed4d868aa74ad1019dfd5160a"
            }
          ],
          "repo": "https://github.com/modelcontextprotocol/go-sdk",
          "type": "GIT"
        }
      ]
    }
  ],
  "aliases": [
    "GHSA-89xv-2j6f-qhc8"
  ],
  "database_specific": {
    "cna_assigner": "GitHub_M",
    "cwe_ids": [
      "CWE-352"
    ],
    "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/33xxx/CVE-2026-33252.json"
  },
  "details": "The Go MCP SDK used Go's standard encoding/json. Prior to version 1.4.1, the Go SDK's Streamable HTTP transport accepted browser-generated cross-site `POST` requests without validating the `Origin` header and without requiring `Content-Type: application/json`. In deployments without Authorization, especially stateless or sessionless configurations, this allows an arbitrary website to send MCP requests to a local server and potentially trigger tool execution. Version 1.4.1 contains a patch for the issue.",
  "id": "CVE-2026-33252",
  "modified": "2026-04-01T23:10:05.793617679Z",
  "published": "2026-03-23T23:44:16.106Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/33xxx/CVE-2026-33252.json"
    },
    {
      "type": "FIX",
      "url": "https://github.com/modelcontextprotocol/go-sdk/commit/a433a831d6e5d5ac3b9e625a8095aa8eaa040dfc"
    },
    {
      "type": "ADVISORY",
      "url": "https://github.com/modelcontextprotocol/go-sdk/security/advisories/GHSA-89xv-2j6f-qhc8"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-33252"
    }
  ],
  "schema_version": "1.7.3",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:H/A:L",
      "type": "CVSS_V3"
    }
  ],
  "summary": "MCP Go SDK Allows Cross-Site Tool Execution for HTTP Servers without Authorizatrion"
}