CVE-2026-104850

{
  "etk_id": "ETK-2026-787",
  "cve_id": "CVE-2026-104850",
  "display_id": "CVE-2026-104850",
  "ghsa_id": "GHSA-6qxp-vccf-f47h",
  "euvd_id": "EUVD-2026-93491",
  "status": "published",
  "anchor_state": "anchored",
  "title": "OAuth issuer-binding flaw in MCP TypeScript SDK",
  "summary": "MCP TypeScript SDK OAuth clients in affected releases can send retained OAuth credentials to an authorization endpoint selected by an untrusted MCP server. This requires an OAuth-enabled HTTP client to connect to a server it does not fully trust while holding credentials for another authorization service; SDK-built servers and stdio clients are not affected.",
  "mitigation": "Upgrade `@modelcontextprotocol/sdk` to 1.31.0 or later, or `@modelcontextprotocol/client` to 2.2.0 or later; also upgrade `@modelcontextprotocol/core` to 2.2.0 or later when it is imported directly. Configure `expectedIssuer` for bundled providers, add an issuer to retained credentials or clear them for reauthentication, and rotate secrets or revoke tokens if an untrusted server may have been contacted.",
  "vendor": "npm",
  "product": "npm:@modelcontextprotocol/sdk",
  "affected": [
    {
      "affected_notes": [],
      "affected_ranges": [
        ">= 1.12.0, < 1.31.0"
      ],
      "ecosystem": "npm",
      "fixed_versions": [
        "1.31.0"
      ],
      "package_name": "@modelcontextprotocol/sdk",
      "purl": "pkg:npm/@modelcontextprotocol/sdk"
    },
    {
      "affected_notes": [],
      "affected_ranges": [
        ">= 2.0.0, < 2.2.0"
      ],
      "ecosystem": "npm",
      "fixed_versions": [
        "2.2.0"
      ],
      "package_name": "@modelcontextprotocol/client",
      "purl": "pkg:npm/@modelcontextprotocol/client"
    }
  ],
  "cwes": null,
  "cvss_score": 7.5,
  "cvss_src": "cna_vendor",
  "cvss_vector": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N",
  "epss_score": 0.0018,
  "epss_percentile": 0.0669,
  "epss_asof": "2026-10-20",
  "automation": "contextual",
  "check": false,
  "check_confidence_basis": null,
  "exploit": false,
  "pipeline_minutes": 16.12133325,
  "t0_at": "2026-10-06T16:08:21.514000+00:00",
  "signals": {
    "trigger_signal": {
      "at": "2026-10-06T15:35:44+00:00",
      "days": -0.022656412037037037,
      "is_lower_bound": false,
      "measured_at": "2026-10-06T16:08:21.514000+00:00",
      "url": "https://github.com/advisories/GHSA-6qxp-vccf-f47h"
    }
  }
}