CVE-2026-1117716.8MediumCWE-863

CVE-2026-111771: Model Context Protocol TypeScript SDK: Server bearer authentication accepted tokens issued for another service

modelcontextprotocol · typescript-sdk

Affected: modelcontextprotocol typescript-sdk · Exploitation: unlikely (under 1%)

Not in CyberSIXT coverage yet: no article names this CVE. This page shows the public record.

0.5%probability of exploitation in the next 30 days

46th percentile

050100

Higher than 46% of scored CVEs

6.8MediumCVSS 3.1

LowMediumHighCrit.

DescriptionCVE.org

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.

Affected products5

From the CVE record. A product or version that is not listed is unknown, not unaffected.

modelcontextprotocol · typescript-sdk>= 1.6.0, < 1.32.0
@modelcontextprotocol · sdk>= 1.6.0, < 1.32.0
@modelcontextprotocol · server>= 2.0.0, < 2.3.0
@modelcontextprotocol · express>= 2.0.0, < 2.0.2
@modelcontextprotocol · server-legacy>= 2.0.0, < 2.3.1

On the Atlas

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Open the Atlas

Exploitation: Unlikely (under 1%). EPSS under 1%, or no score yet.
CISA KEV: Not listed
Public check: No public nuclei template
Weakness: Incorrect Authorization · Access Control
Vendor: modelcontextprotocol
Published: November 2026
Band: Unlikely (under 1%), November 2026

CoverageNo articles yet

No CyberSIXT article names CVE-2026-111771 yet, so there is no coverage timeline, action brief or change log for it. Everything on this page comes from the public CVE record, CISA KEV, EPSS and the nuclei template index. Search the archive or see the CVEs in the news.