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CVE-2026-104850— MCP TypeScript SDK: OAuth client could send credentials to an authorization server chosen by the MCP server

Quick assessment

Affected
modelcontextprotocol typescript-sdk
Exploitation
No confirmed in-the-wild exploitation; assess based on exposure
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

以下是该漏洞描述信息的中文翻译： --- MCP TypeScript SDK 是 Model Context Protocol（模型上下文协议）服务器和客户端的官方 TypeScript SDK。从版本 1.12.0 开始，直到版本 1.31.0 和 2.2.0 之前，该 SDK 的 OAuth 客户端支持允许 MCP 服务器与其连接的客户端共同决定哪个授权服务器可以接收客户端的 OAuth 凭证。这些预先配置和预置的凭证并未绑定到它们所属的授权服务器。一个恶意或被入侵的 MCP 服务器可以在其受保护的资源元数据

CVSS 7.5 · High

Possible ATT&CK Techniques 1 AI

T1552.001 · Credentials In Files

Affected Version Matrix 2

VendorProduct Version RangeStatus
modelcontextprotocol typescript-sdk >= 1.12.0, < 1.31.0 affected
>= 2.0.0, < 2.2.0 affected
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I. Basic Information for CVE-2026-104850

Vulnerability Information
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Vulnerability Title
MCP TypeScript SDK: OAuth client could send credentials to an authorization server chosen by the MCP server
Source: CVE Program / CVE List V5
Vulnerability Description
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.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N
Source: CVE Program / CVE List V5
Vulnerability Type
对数据真实性的验证不充分
Source: CVE Program / CVE List V5

Affected Products

Vendor Product Affected Versions CPE Subscribe
modelcontextprotocol typescript-sdk >= 1.12.0, < 1.31.0 -

II. Public POCs for CVE-2026-104850

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III. Intelligence Information for CVE-2026-104850

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Patches & Fixes for CVE-2026-104850 (1)

Vendor Advisories for CVE-2026-104850 (1)

IV. Related Vulnerabilities

Same product: typescript-sdk
Same vendor: modelcontextprotocol
Same weakness: CWE-345

V. Comments for CVE-2026-104850

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