{"id":"CVE-2026-111771","revision":null,"records":[{"revision":"4014f316562243a98f37ff0efd798f36","observedAt":"2026-11-05T22:36:54.207+00:00","statement":{"source":"cve-program","id":"CVE-2026-111771","aliases":[],"title":"Model Context Protocol TypeScript SDK: Server bearer authentication accepted tokens issued for another service","description":"The Model Context Protocol TypeScript SDK provides TypeScript client and server implementations of the Model Context Protocol. From 1.6.0 until 1.32.0 in @modelcontextprotocol/sdk, from 2.0.0 until 2.3.0 in @modelcontextprotocol/server, from 2.0.0 until 2.0.2 in @modelcontextprotocol/express, and from 2.0.0 until 2.3.1 in @modelcontextprotocol/server-legacy, server-side bearer authentication could accept a valid access token issued for a different service because the SDK did not enforce the token audience. The affected surface is server-side HTTP bearer authentication. The trigger is a valid token whose audience names another service. The authorization server must issue tokens for multiple services, and the application's verifyAccessToken() must not independently validate aud. Applications already validating aud inside verifyAccessToken() are not affected. An attacker with a token for another service could authenticate to the MCP server and obtain the confidentiality and integrity capabilities granted to an authenticated caller. Upgrading alone leaves the new audience validation disabled. Operators must enable audience validation and provide the token audience together. Enabling only the expected audience check causes every request to receive HTTP 401. This issue is fixed in @modelcontextprotocol/sdk 1.32.0, @modelcontextprotocol/server 2.3.0, @modelcontextprotocol/express 2.0.2, and @modelcontextprotocol/server-legacy 2.3.1.","state":0,"publishedAt":"2026-11-05T21:08:55.758+00:00","modifiedAt":"2026-11-05T21:08:55.758+00:00","affected":[{"ecosystem":"Vendor product","name":"typescript-sdk","ranges":[],"versions":[],"rawVersionEvidence":"{\n                    \"vendor\": \"modelcontextprotocol\",\n                    \"product\": \"typescript-sdk\",\n                    \"versions\": [\n                        {\n                            \"version\": \">= 1.6.0, < 1.32.0\",\n                            \"status\": \"affected\"\n                        }\n                    ]\n                }"},{"ecosystem":"Vendor product","name":"sdk","ranges":[],"versions":[],"rawVersionEvidence":"{\n                    \"vendor\": \"@modelcontextprotocol\",\n                    \"product\": \"sdk\",\n                    \"versions\": [\n                        {\n                            \"version\": \">= 1.6.0, < 1.32.0\",\n                            \"status\": \"affected\"\n                        }\n                    ]\n                }"},{"ecosystem":"Vendor product","name":"server","ranges":[],"versions":[],"rawVersionEvidence":"{\n                    \"vendor\": \"@modelcontextprotocol\",\n                    \"product\": \"server\",\n                    \"versions\": [\n                        {\n                            \"version\": \">= 2.0.0, < 2.3.0\",\n                            \"status\": \"affected\"\n                        }\n                    ]\n                }"},{"ecosystem":"Vendor product","name":"express","ranges":[],"versions":[],"rawVersionEvidence":"{\n                    \"vendor\": \"@modelcontextprotocol\",\n                    \"product\": \"express\",\n                    \"versions\": [\n                        {\n                            \"version\": \">= 2.0.0, < 2.0.2\",\n                            \"status\": \"affected\"\n                        }\n                    ]\n                }"},{"ecosystem":"Vendor product","name":"server-legacy","ranges":[],"versions":[],"rawVersionEvidence":"{\n                    \"vendor\": \"@modelcontextprotocol\",\n                    \"product\": \"server-legacy\",\n                    \"versions\": [\n                        {\n                            \"version\": \">= 2.0.0, < 2.3.1\",\n                            \"status\": \"affected\"\n                        }\n                    ]\n                }"}],"metrics":[{"system":"CVSS 3.1","vector":"CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:N","score":6.8,"severity":"MEDIUM"}],"references":["https://github.com/modelcontextprotocol/typescript-sdk/security/advisories/GHSA-rvq5-wwqv-78pq","https://github.com/modelcontextprotocol/typescript-sdk/pull/2929","https://github.com/modelcontextprotocol/typescript-sdk/pull/2930","https://github.com/modelcontextprotocol/typescript-sdk/pull/2952","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/releases/tag/1.32.0","https://github.com/modelcontextprotocol/typescript-sdk/releases/tag/@modelcontextprotocol/express@2.0.2","https://github.com/modelcontextprotocol/typescript-sdk/releases/tag/@modelcontextprotocol/server-legacy@2.3.1","https://github.com/modelcontextprotocol/typescript-sdk/releases/tag/@modelcontextprotocol/server@2.3.0"],"sourceUrl":"https://www.cve.org/CVERecord?id=CVE-2026-111771","license":"CVE Program Terms of Use","key":"cve-program:CVE-2026-111771","identifiers":["CVE-2026-111771"]},"retained":false,"historicalAffected":[]},{"revision":"ba7c43346bf148888bfdbe23f8188a4b","observedAt":"2026-11-07T04:33:10.09+00:00","statement":{"source":"euvd","id":"EUVD-2026-117801","aliases":["CVE-2026-111771","GHSA-rvq5-wwqv-78pq"],"title":"The Model Context Protocol TypeScript SDK provides TypeScript client and server implementations of the Model Context Protocol. From 1.6.0 until 1.32.0 in @modelcontextprotocol/sdk, from 2.0.0 until 2.3.0 in @modelcontextprotocol/server, fro…","description":"The Model Context Protocol TypeScript SDK provides TypeScript client and server implementations of the Model Context Protocol. From 1.6.0 until 1.32.0 in @modelcontextprotocol/sdk, from 2.0.0 until 2.3.0 in @modelcontextprotocol/server, from 2.0.0 until 2.0.2 in @modelcontextprotocol/express, and from 2.0.0 until 2.3.1 in @modelcontextprotocol/server-legacy, server-side bearer authentication could accept a valid access token issued for a different service because the SDK did not enforce the token audience. The affected surface is server-side HTTP bearer authentication. The trigger is a valid token whose audience names another service. The authorization server must issue tokens for multiple services, and the application's verifyAccessToken() must not independently validate aud. Applications already validating aud inside verifyAccessToken() are not affected. An attacker with a token for another service could authenticate to the MCP server and obtain the confidentiality and integrity capabilities granted to an authenticated caller. Upgrading alone leaves the new audience validation disabled. Operators must enable audience validation and provide the token audience together. Enabling only the expected audience check causes every request to receive HTTP 401. This issue is fixed in @modelcontextprotocol/sdk 1.32.0, @modelcontextprotocol/server 2.3.0, @modelcontextprotocol/express 2.0.2, and @modelcontextprotocol/server-legacy 2.3.1.","state":0,"publishedAt":null,"modifiedAt":null,"affected":[],"metrics":[{"system":"EUVD CVSS 3.1","vector":"CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:N","score":6.8,"severity":null}],"references":["https://github.com/modelcontextprotocol/typescript-sdk/security/advisories/GHSA-rvq5-wwqv-78pq","https://github.com/modelcontextprotocol/typescript-sdk/pull/2929","https://github.com/modelcontextprotocol/typescript-sdk/pull/2930","https://github.com/modelcontextprotocol/typescript-sdk/pull/2952","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/releases/tag/1.32.0","https://github.com/modelcontextprotocol/typescript-sdk/releases/tag/@modelcontextprotocol/express@2.0.2","https://github.com/modelcontextprotocol/typescript-sdk/releases/tag/@modelcontextprotocol/server-legacy@2.3.1","https://github.com/modelcontextprotocol/typescript-sdk/releases/tag/@modelcontextprotocol/server@2.3.0"],"sourceUrl":"https://euvd.enisa.europa.eu/vulnerability/EUVD-2026-117801","license":"ENISA EUVD · source terms and attribution apply","enrichment":{"sourceStatus":null,"weaknesses":[],"productCriteria":[],"sourceDates":{"datePublished":"Nov 5, 2026, 9:08:55 PM","dateUpdated":"Nov 5, 2026, 9:08:55 PM"},"relatedAdvisories":[],"note":"EUVD source date text has no stated timezone and is retained without inventing a UTC instant. Related bulletin membership is not an alias, common cause or applicability claim. A missing vector with a zero score is treated as unrated. Complete vendor/product and underlying source evidence remains in the original JSON."},"key":"euvd:EUVD-2026-117801","identifiers":["EUVD-2026-117801","CVE-2026-111771","GHSA-rvq5-wwqv-78pq"]},"retained":false,"historicalAffected":[]},{"revision":"f23d9f90166e484fa847fd0595e10ec2","observedAt":"2026-11-06T09:36:27.137+00:00","statement":{"source":"nvd","id":"CVE-2026-111771","aliases":[],"title":"The Model Context Protocol TypeScript SDK provides TypeScript client and server implementations of the Model Context Protocol. From 1.6.0 until 1.32.0 in @modelcontextprotocol/sdk, from 2.0.0 until 2.3.0 in @modelcontextprotocol/server, fro…","description":"The Model Context Protocol TypeScript SDK provides TypeScript client and server implementations of the Model Context Protocol. From 1.6.0 until 1.32.0 in @modelcontextprotocol/sdk, from 2.0.0 until 2.3.0 in @modelcontextprotocol/server, from 2.0.0 until 2.0.2 in @modelcontextprotocol/express, and from 2.0.0 until 2.3.1 in @modelcontextprotocol/server-legacy, server-side bearer authentication could accept a valid access token issued for a different service because the SDK did not enforce the token audience. The affected surface is server-side HTTP bearer authentication. The trigger is a valid token whose audience names another service. The authorization server must issue tokens for multiple services, and the application's verifyAccessToken() must not independently validate aud. Applications already validating aud inside verifyAccessToken() are not affected. An attacker with a token for another service could authenticate to the MCP server and obtain the confidentiality and integrity capabilities granted to an authenticated caller. Upgrading alone leaves the new audience validation disabled. Operators must enable audience validation and provide the token audience together. Enabling only the expected audience check causes every request to receive HTTP 401. This issue is fixed in @modelcontextprotocol/sdk 1.32.0, @modelcontextprotocol/server 2.3.0, @modelcontextprotocol/express 2.0.2, and @modelcontextprotocol/server-legacy 2.3.1.","state":0,"publishedAt":"2026-11-05T21:18:35.973+00:00","modifiedAt":"2026-11-05T21:18:35.973+00:00","affected":[],"metrics":[{"system":"CVSS 3.1 · security-advisories@github.com · Secondary","vector":"CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:N","score":6.8,"severity":"MEDIUM"}],"references":["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/pull/2929","https://github.com/modelcontextprotocol/typescript-sdk/pull/2930","https://github.com/modelcontextprotocol/typescript-sdk/pull/2952","https://github.com/modelcontextprotocol/typescript-sdk/releases/tag/1.32.0","https://github.com/modelcontextprotocol/typescript-sdk/releases/tag/@modelcontextprotocol/express@2.0.2","https://github.com/modelcontextprotocol/typescript-sdk/releases/tag/@modelcontextprotocol/server-legacy@2.3.1","https://github.com/modelcontextprotocol/typescript-sdk/releases/tag/@modelcontextprotocol/server@2.3.0","https://github.com/modelcontextprotocol/typescript-sdk/security/advisories/GHSA-rvq5-wwqv-78pq"],"sourceUrl":"https://nvd.nist.gov/vuln/detail/CVE-2026-111771","license":"NIST NVD usage terms; underlying source attribution retained","enrichment":{"sourceStatus":"Received","weaknesses":["CWE-863"],"productCriteria":[],"sourceDates":{"published":"2026-11-05T21:18:35.973","lastModified":"2026-11-05T21:18:35.973"},"relatedAdvisories":[],"note":"NVD analysis and CPE criteria are source context, not proof that a package or your environment is affected. Complete affected data, logical configurations and SSVC are retained in the original JSON."},"key":"nvd:CVE-2026-111771","identifiers":["CVE-2026-111771"]},"retained":false,"historicalAffected":[]},{"revision":"07d51d5b53514c29bbee12095e79d8bc","observedAt":"2026-10-24T13:17:17.793+00:00","statement":{"source":"osv","id":"GHSA-rvq5-wwqv-78pq","aliases":["CVE-2026-111771"],"title":"MCP TypeScript SDK: Server bearer authentication accepted tokens issued for another service","description":"### Summary\nIn 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.\n\n### Am I affected?\nYes, 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.\n\nAffected versions:\n\n- `@modelcontextprotocol/sdk` 1.6.0 through 1.31.0\n- `@modelcontextprotocol/server` 2.0.0 through 2.2.0\n- `@modelcontextprotocol/express` 2.0.0 through 2.0.1\n- `@modelcontextprotocol/server-legacy` 2.0.0 through 2.3.0\n\n### Fix\nUpgrade to:\n\n- 1.x: `@modelcontextprotocol/sdk` 1.32.0 or later\n- 2.x: `@modelcontextprotocol/server` 2.3.0 or later, together with `@modelcontextprotocol/express` 2.0.2 or later if you use it\n- `@modelcontextprotocol/server-legacy` 2.3.1 or later\n\n**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:\n\n1. Pass the audience your authorization server puts in tokens for your server: `requireBearerAuth({ verifier, expectedResource: new URL('https://mcp.example.com/mcp') })`.\n2. Return the token's audience from `verifyAccessToken()` as `AuthInfo.resource`, also a `URL`.\n\nA token for another service then gets `401`. With only the first change, every request gets `401`.\n\nIf you cannot upgrade yet, reject any token whose `aud` does not include your server inside `verifyAccessToken()`. That closes the issue on every version.","state":0,"publishedAt":"2026-10-20T19:43:36+00:00","modifiedAt":"2026-10-20T20:00:04.5953099+00:00","affected":[{"ecosystem":"npm","name":"@modelcontextprotocol/sdk","ranges":[{"type":"SEMVER","events":[{"kind":"introduced","version":"1.6.0"},{"kind":"fixed","version":"1.32.0"}]}],"versions":[],"rawVersionEvidence":null},{"ecosystem":"npm","name":"@modelcontextprotocol/server","ranges":[{"type":"SEMVER","events":[{"kind":"introduced","version":"2.0.0"},{"kind":"fixed","version":"2.3.0"}]}],"versions":[],"rawVersionEvidence":null},{"ecosystem":"npm","name":"@modelcontextprotocol/express","ranges":[{"type":"SEMVER","events":[{"kind":"introduced","version":"2.0.0"},{"kind":"fixed","version":"2.0.2"}]}],"versions":[],"rawVersionEvidence":null},{"ecosystem":"npm","name":"@modelcontextprotocol/server-legacy","ranges":[{"type":"SEMVER","events":[{"kind":"introduced","version":"2.0.0"},{"kind":"fixed","version":"2.3.1"}]}],"versions":[],"rawVersionEvidence":null}],"metrics":[{"system":"CVSS_V3","vector":"CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:N","score":null,"severity":null},{"system":"Publisher rating","vector":null,"score":null,"severity":"MODERATE"}],"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"],"sourceUrl":"https://github.com/advisories/GHSA-rvq5-wwqv-78pq","license":"GitHub Advisory Database · CC-BY-4.0","key":"osv:GHSA-rvq5-wwqv-78pq","identifiers":["GHSA-rvq5-wwqv-78pq","CVE-2026-111771"]},"retained":false,"historicalAffected":[]}],"coverage":[{"source":"cisa-kev:global","scope":"Complete CISA KEV catalog; all vendors. Missing entries do not establish absence of exploitation.","generation":"2026-11-08T12:04:37.5111605+00:00","complete":true,"records":1769,"lastAttemptAt":"2026-11-08T12:04:37.5111605+00:00","lastSuccessAt":"2026-11-08T12:04:37.723623+00:00","error":null,"lastVerifiedAt":"2026-11-08T12:04:37.7236261+00:00","snapshotPublishedAt":null,"importing":false,"stagedRecords":0,"checkedIdentifiers":null,"expectedIdentifiers":null,"failedIdentifiers":null},{"source":"cve-program","scope":"Official CVE Program baseline and cumulative hourly delta; all vendors, published and rejected records","generation":"cve-eaa64dac63caa79c8d4905619258c41c51b39e461b996124e1a21b5e85e7e738-2b67187422a694a3d3288b6a1e28326b3060bb18a3ee01d9be7309c46446a822","complete":true,"records":421097,"lastAttemptAt":"2026-11-08T12:04:36.9953395+00:00","lastSuccessAt":"2026-11-08T12:04:36.9557955+00:00","error":null,"lastVerifiedAt":"2026-11-08T12:04:36.9953395+00:00","snapshotPublishedAt":"2026-11-08T11:26:20+00:00","importing":false,"stagedRecords":0,"checkedIdentifiers":null,"expectedIdentifiers":null,"failedIdentifiers":null},{"source":"euvd","scope":"Rolling EUVD lookups of CVE aliases in current public OSV archives; 500 identifiers per refresh, rechecked after 48 hours. Not a global EUVD catalog. Successful not-found lookups count as checked; they do not imply withdrawal or safety. No reader inventory is sent.","generation":"enrichment-86f25219fb644e6286aef55d85e25bf2","complete":true,"records":13654,"lastAttemptAt":"2026-11-08T12:05:08.2403712+00:00","lastSuccessAt":"2026-11-08T11:08:04.005+00:00","error":null,"lastVerifiedAt":"2026-11-08T11:08:04.005+00:00","snapshotPublishedAt":null,"importing":false,"stagedRecords":0,"checkedIdentifiers":13706,"expectedIdentifiers":13706,"failedIdentifiers":0},{"source":"first-epss:nuget","scope":"FIRST EPSS for explicit CVE aliases in the collected public NuGet archive. Not a global EPSS backfill.","generation":"2026-11-08T12:04:37.5111605+00:00","complete":true,"records":1096,"lastAttemptAt":"2026-11-08T12:04:37.5111605+00:00","lastSuccessAt":"2026-11-08T12:04:37.7247541+00:00","error":null,"lastVerifiedAt":"2026-11-08T12:04:37.7247552+00:00","snapshotPublishedAt":null,"importing":false,"stagedRecords":0,"checkedIdentifiers":null,"expectedIdentifiers":null,"failedIdentifiers":null},{"source":"nvd","scope":"Rolling NVD lookups of CVE aliases in current public OSV archives; 500 identifiers per refresh, rechecked after 48 hours. Not a global NVD catalog. Successful not-found lookups count as checked; they do not imply withdrawal or safety. No reader inventory is sent.","generation":"enrichment-c8ab24cce7724539b5148423668d4a8d","complete":false,"records":13666,"lastAttemptAt":"2026-11-08T12:05:07.5124328+00:00","lastSuccessAt":"2026-11-08T12:05:07.509+00:00","error":null,"lastVerifiedAt":"2026-11-08T12:05:07.509+00:00","snapshotPublishedAt":null,"importing":false,"stagedRecords":0,"checkedIdentifiers":13685,"expectedIdentifiers":13706,"failedIdentifiers":0},{"source":"osv:Go","scope":"Complete OSV Go ecosystem archive, including withdrawn and malicious-package source records; statement counts are not unique CVE counts","generation":"go-980593e6977a6d1b4fb1eed5a1ffe88a468736f89f0a06f710924ad59132c023","complete":true,"records":9914,"lastAttemptAt":"2026-11-08T12:04:37.4138776+00:00","lastSuccessAt":"2026-11-08T11:07:07.068788+00:00","error":null,"lastVerifiedAt":"2026-11-08T12:04:37.4138776+00:00","snapshotPublishedAt":"2026-11-08T11:02:46+00:00","importing":false,"stagedRecords":0,"checkedIdentifiers":null,"expectedIdentifiers":null,"failedIdentifiers":null},{"source":"osv:NuGet","scope":"Complete OSV NuGet ecosystem archive, including GitHub Advisory Database records; NuGet version matching only","generation":"nuget-fde804134ecdda0ddd5ff5c26ee1fff5a6fa659311f7ef2e51c6ad54964db0e2","complete":true,"records":1971,"lastAttemptAt":"2026-11-08T12:04:37.186742+00:00","lastSuccessAt":"2026-11-06T19:03:17.0399903+00:00","error":null,"lastVerifiedAt":"2026-11-08T12:04:37.186742+00:00","snapshotPublishedAt":"2026-11-06T18:17:57+00:00","importing":false,"stagedRecords":0,"checkedIdentifiers":null,"expectedIdentifiers":null,"failedIdentifiers":null},{"source":"osv:crates.io","scope":"Complete OSV crates.io ecosystem archive, including withdrawn and malicious-package source records; statement counts are not unique CVE counts","generation":"crates.io-964c14035e6f0f6478b2870fad6a7ef9f6045876d4a12af2c2e514521e54b6af","complete":true,"records":3055,"lastAttemptAt":"2026-11-08T12:04:37.4417198+00:00","lastSuccessAt":"2026-11-08T11:07:12.1927025+00:00","error":null,"lastVerifiedAt":"2026-11-08T12:04:37.4417198+00:00","snapshotPublishedAt":"2026-11-08T11:02:46+00:00","importing":false,"stagedRecords":0,"checkedIdentifiers":null,"expectedIdentifiers":null,"failedIdentifiers":null},{"source":"osv:npm","scope":"Complete OSV npm ecosystem archive, including withdrawn and malicious-package source records; statement counts are not unique CVE counts","generation":"npm-f8647d7ba64b1ba0dfdc7130944766d5b36d5b77d18fff0c79e651a4cff3c2b9","complete":true,"records":231293,"lastAttemptAt":"2026-11-08T12:04:37.3024645+00:00","lastSuccessAt":"2026-11-08T11:06:56.2918717+00:00","error":null,"lastVerifiedAt":"2026-11-08T12:04:37.3024645+00:00","snapshotPublishedAt":"2026-11-08T11:02:50+00:00","importing":false,"stagedRecords":0,"checkedIdentifiers":null,"expectedIdentifiers":null,"failedIdentifiers":null}]}