MCP TypeScript SDK: Server bearer authentication accepted tokens issued for another service

{
  "id": "fa4d7a7bd822a2c6314f6fa2f46f99df8a387e2cc5f91cd85c3540ee0d14eab7",
  "url": "https://osv.dev/vulnerability/GHSA-rvq5-wwqv-78pq",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "MCP TypeScript SDK: Server bearer authentication accepted tokens issued for another service",
    "summary": "### Summary In affected versions, the SDK's server-side bearer authentication had no way to check that a token was issued for your server (its audience). Where one authorization server issues tokens for several services, a valid token for another service was also accepted by your MCP server. ### Am I affected? Yes, if your HTTP server uses `requireBearerAuth()` or `verifyBearerToken()`, its authorization server also issues tokens for other services, and your `verifyAccessToken()` does not check the token's audience (`aud`) itself. Affected versions: - `@modelcontextprotocol/sdk` 1.6.0 through 1.31.0 - `@modelcontextprotocol/server` 2.0.0 through 2.2.0 - `@modelcontextprotocol/express` 2.0.0 through 2.0.1 - `@modelcontextprotocol/server-legacy` 2.0.0 through 2.3.0 ### Fix Upgrade to: - 1.x: `@modelcontextprotocol/sdk` 1.32.0 or later - 2.x: `@modelcontextprotocol/server` 2.3.0 or later, together with `@modelcontextprotocol/express` 2.0.2 or later if you use it - `@modelcontextprotocol/server-legacy` 2.3.1 or later **Upgrading alone changes nothing.** The patched versions add an `expectedResource` setting that is off by default. To turn the check on, make both of these changes together: 1. Pass the audience your authorization server puts in tokens for your server: `requireBearerAuth({ verifier, expectedResource: new URL('https://mcp.example.com/mcp') })`. 2. Return the token's audience from `verifyAccessToken()` as `AuthInfo.resource`, also a `URL`. A token for another service ",
    "evidence": "osv:GHSA-rvq5-wwqv-78pq",
    "products": [
      {
        "name": {
          "value": "@modelcontextprotocol/sdk",
          "evidence": "/affected/0/package/name"
        },
        "prerequisites": [],
        "fixed_versions": [
          {
            "value": "1.32.0",
            "evidence": "/affected/0/ranges"
          }
        ],
        "affected_versions": []
      },
      {
        "name": {
          "value": "@modelcontextprotocol/server",
          "evidence": "/affected/1/package/name"
        },
        "prerequisites": [],
        "fixed_versions": [
          {
            "value": "2.3.0",
            "evidence": "/affected/1/ranges"
          }
        ],
        "affected_versions": []
      },
      {
        "name": {
          "value": "@modelcontextprotocol/express",
          "evidence": "/affected/2/package/name"
        },
        "prerequisites": [],
        "fixed_versions": [
          {
            "value": "2.0.2",
            "evidence": "/affected/2/ranges"
          }
        ],
        "affected_versions": []
      },
      {
        "name": {
          "value": "@modelcontextprotocol/server-legacy",
          "evidence": "/affected/3/package/name"
        },
        "prerequisites": [],
        "fixed_versions": [
          {
            "value": "2.3.1",
            "evidence": "/affected/3/ranges"
          }
        ],
        "affected_versions": []
      }
    ],
    "severity": "medium",
    "structured": {
      "id": "GHSA-rvq5-wwqv-78pq",
      "aliases": [
        "CVE-2026-111771",
        "GHSA-rvq5-wwqv-78pq"
      ],
      "metrics": [
        {
          "type": "CVSS_V3",
          "score": "CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:N"
        }
      ],
      "affected": [
        {
          "ranges": [
            {
              "type": "SEMVER",
              "events": [
                {
                  "introduced": "1.6.0"
                },
                {
                  "fixed": "1.32.0"
                }
              ]
            }
          ],
          "package": {
            "name": "@modelcontextprotocol/sdk",
            "purl": "pkg:npm/%40modelcontextprotocol/sdk",
            "ecosystem": "npm"
          },
          "database_specific": {
            "source": "https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2026/10/GHSA-rvq5-wwqv-78pq/GHSA-rvq5-wwqv-78pq.json"
          }
        },
        {
          "ranges": [
            {
              "type": "SEMVER",
              "events": [
                {
                  "introduced": "2.0.0"
                },
                {
                  "fixed": "2.3.0"
                }
              ]
            }
          ],
          "package": {
            "name": "@modelcontextprotocol/server",
            "purl": "pkg:npm/%40modelcontextprotocol/server",
            "ecosystem": "npm"
          },
          "database_specific": {
            "source": "https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2026/10/GHSA-rvq5-wwqv-78pq/GHSA-rvq5-wwqv-78pq.json"
          }
        },
        {
          "ranges": [
            {
              "type": "SEMVER",
              "events": [
                {
                  "introduced": "2.0.0"
                },
                {
                  "fixed": "2.0.2"
                }
              ]
            }
          ],
          "package": {
            "name": "@modelcontextprotocol/express",
            "purl": "pkg:npm/%40modelcontextprotocol/express",
            "ecosystem": "npm"
          },
          "database_specific": {
            "source": "https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2026/10/GHSA-rvq5-wwqv-78pq/GHSA-rvq5-wwqv-78pq.json"
          }
        },
        {
          "ranges": [
            {
              "type": "SEMVER",
              "events": [
                {
                  "introduced": "2.0.0"
                },
                {
                  "fixed": "2.3.1"
                }
              ]
            }
          ],
          "package": {
            "name": "@modelcontextprotocol/server-legacy",
            "purl": "pkg:npm/%40modelcontextprotocol/server-legacy",
            "ecosystem": "npm"
          },
          "database_specific": {
            "source": "https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2026/10/GHSA-rvq5-wwqv-78pq/GHSA-rvq5-wwqv-78pq.json"
          }
        }
      ],
      "modified": "2026-10-20T20:00:04.595309934Z",
      "provider": "osv",
      "references": [
        "https://github.com/modelcontextprotocol/typescript-sdk/security/advisories/GHSA-rvq5-wwqv-78pq",
        "https://github.com/modelcontextprotocol/typescript-sdk/commit/40f8f4e229d963cd7fd2890bda2aeebe7005299a",
        "https://github.com/modelcontextprotocol/typescript-sdk/commit/5a0724d14cf34a27a3b070224d2996cdd611df9f",
        "https://github.com/modelcontextprotocol/typescript-sdk/commit/5a1867390b91b8836f49af76c45427279f513325",
        "https://github.com/modelcontextprotocol/typescript-sdk"
      ],
      "provider_metadata": {
        "cwe_ids": [
          "CWE-863"
        ],
        "severity": "MODERATE",
        "github_reviewed": true,
        "nvd_published_at": null,
        "github_reviewed_at": "2026-10-20T19:43:36Z"
      }
    },
    "related_cves": [
      {
        "value": "CVE-2026-111771",
        "evidence": "/aliases"
      }
    ],
    "security_relevant": true,
    "severity_evidence": "/severity/0/score"
  },
  "source_id": "core-osv",
  "document_id": 390361,
  "published_at": "2026-10-20T19:43:36+00:00"
}