{"data":{"id":"5338d8af-4f70-4945-962c-1841355d015b","title":"GHSA-w4fh-qvv9-3v23: Model Context Protocol Python SDK: Server bearer-token authentication accepts tokens issued for a different resource server","summary":"The MCP Python SDK's server-side bearer authentication did not check that a token was issued for the receiving server (its audience). Where one authorization server issues tokens for several services, a valid token for another service was accepted by the MCP server. Affected versions are mcp 1.10.0 through 1.29.1 and 2.0.0 through 2.1.1.","solution":"Upgrade to mcp 1.30.0 or later (1.x) or mcp 2.2.0 or later (2.x), then set validate_token_resource=True in AuthSettings with resource_server_url set to the audience the authorization server puts in tokens, and return the token's audience from verify_token() as AccessToken.resource. Upgrading alone changes nothing. If your TokenVerifier already checks the audience, set validate_token_resource=False to silence the deprecation warning. If you cannot upgrade yet, reject any token whose aud does not include your server inside verify_token().","labels":["security"],"sourceUrl":"https://github.com/advisories/GHSA-w4fh-qvv9-3v23","publishedAt":"2026-10-27T21:06:59.000Z","cveId":"CVE-2026-116684","cweIds":null,"cvssScore":null,"cvssSeverity":"medium","severity":"medium","attackType":["other"],"issueType":"vulnerability","affectedPackages":["mcp@>= 1.10.0, < 1.30.0 (fixed: 1.30.0)","mcp@>= 2.0.0, < 2.2.0 (fixed: 2.2.0)"],"affectedPackageNames":["mcp"],"affectedPackageRefs":["pypi:mcp"],"affectedVendors":["Anthropic"],"affectedVendorsRaw":["Model Context Protocol Python SDK"],"classifierModel":"claude-haiku-5-5","classifierPromptVersion":"v4","summaryPromptVersion":"v2","headline":null,"headlinePromptVersion":null,"cvssVector":null,"attackVector":null,"attackComplexity":null,"privilegesRequired":null,"userInteraction":null,"exploitMaturity":"unknown","epssScore":0,"epssCheckedAt":"2026-10-28T00:05:48.674Z","kevDateAdded":null,"advisoryAliases":["GHSA-w4fh-qvv9-3v23"],"affectedPackagesSource":null,"affectedPackagesCheckedAt":null,"patchAvailable":true,"disclosureDate":"2026-10-27T21:06:59.000Z","capecIds":null,"crossRefCount":0,"attackSophistication":"moderate","impactType":["confidentiality","integrity"],"aiComponentTargeted":"api","llmSpecific":false,"classifierConfidence":0.9,"researchCategory":null,"atlasIds":null}}