Reference implementation Data compiled from public sources as of 2026-10-26. Not an assessment, certification or recommendation. Confirm current status with the vendor and the issuing body.
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CVEs / CVE-2026-104850

Protocol implementation

CVE-2026-104850

High · CVSS 3.1 7.5 Credential access

MCP TypeScript SDK is the official TypeScript SDK for Model Context Protocol servers and clients. Starting in version 1.12.0 and prior to versions 1.31.0 and 2.2.0, the SDK's OAuth client support let the MCP server a client connected to decide which authorization server received the client's OAuth credentials. Stored and pre-provisioned credentials were not bound to the authorization server they belong to. A malicious or compromised MCP server could name its own authorization server in its protected resource metadata. Without any user interaction, the client would send that server the `refresh_token` and `client_secret` stored from an earlier sign-in (1.x), or the configured `client_secret` or signed assertion of a bundled non-interactive provider (1.x and 2.x). Only those applications that use the SDK as an MCP client over HTTP with an `authProvider`: your own `OAuthClientProvider`, or the bundled `ClientCredentialsProvider`, `PrivateKeyJwtProvider`, `StaticPrivateKeyJwtProvider` or (2.x) `CrossAppAccessProvider` and that may connect to an MCP server the owners does not fully trust while holding credentials for a legitimate authorization server are affected. `@modelcontextprotocol/sdk` 1.31.0 (1.x) and `@modelcontextprotocol/client` 2.2.0 (2.x) patch the issue. A workaround for those who cannot upgrade is available. 2.0.0 and 2.1.0 already accept `expectedIssuer`. On 1.x, the only workaround is to connect OAuth-enabled clients only to MCP servers you trust.

Official record (CVE.org) NVD Export JSON Report a wrong listing

Affected products · 1

ProductVersions affectedFixed in
Anthropic / MCP project: Model Context Protocol SDKs and reference servers not stated by CPE —

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In this registry

References · 4

The official record's references, as NVD lists them, minus any tagged Exploit. Nothing here is an exploit or a proof of concept.

Description, scores, versions and references are the official CVE record's own, retrieved 2026-10-25 from NVD. Category, attack surface and cross-links are this registry's classification and can be wrong — use the button above. Not a severity assessment for your deployment.