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CVE-2026-116684— Model Context Protocol Python SDK: Server bearer-token authentication accepts tokens issued for a different resource server

Quick assessment

Affected
modelcontextprotocol python-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.

Model Context Protocol（MCP）Python SDK 是 MCP 服务器和客户端的官方 Python 开发工具包。在 1.10.0 至 1.30.0 以及 2.2.0 版本中，若通过 配置服务器端 Bearer 身份验证，且使用 进行验证，当授权服务器为多个资源服务，而 未独立验证 （受众）字段时，系统会接受本应颁发给其他服务的有效令牌。此资源混淆漏洞允许令牌持有者向错误的 MCP 服务器进行身份验证，并行使该令牌所赋予的访问权限。该问题已在 1.30.0 和 2.2.0 版本中得到修复。

CVSS 6.8 · Medium

Affected Version Matrix 2

VendorProduct Version RangeStatus
modelcontextprotocol python-sdk >= 1.10.0, < 1.30.0 affected
>= 2.0.0, < 2.2.0 affected
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I. Basic Information for CVE-2026-116684

Vulnerability Information
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Vulnerability Title
Model Context Protocol Python SDK: Server bearer-token authentication accepts tokens issued for a different resource server
Source: CVE Program / CVE List V5
Vulnerability Description
The Model Context Protocol Python SDK is the official Python SDK for Model Context Protocol servers and clients. From 1.10.0 until 1.30.0 and 2.2.0, server-side bearer authentication configured through AuthSettings with token_verifier accepts a valid token issued for another service when the authorization server serves multiple resources and the TokenVerifier does not independently validate the aud audience. This resource-confusion flaw lets a token holder authenticate to the wrong MCP server and exercise that token's resulting access. This issue is fixed in versions 1.30.0 and 2.2.0.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:N
Source: CVE Program / CVE List V5
Vulnerability Type
授权机制不正确
Source: CVE Program / CVE List V5

Affected Products

Vendor Product Affected Versions CPE Subscribe
modelcontextprotocol python-sdk >= 1.10.0, < 1.30.0 -

II. Public POCs for CVE-2026-116684

# POC Description Source Link Shenlong Link
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III. Intelligence Information for CVE-2026-116684

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Other References for CVE-2026-116684 (1)

Other References for CVE-2026-116684 (5)

Same Patch Batch · modelcontextprotocol · 2026-10-27 · 3 CVEs total

CVE-2026-116686 6.5 MEDIUM Model Context Protocol Python SDK: Client fetched server-chosen $ref URLs while validating
CVE-2026-116685 5.9 MEDIUM Model Context Protocol Python SDK: HTTP client transports followed cross-origin redirects

IV. Related Vulnerabilities

Same product: python-sdk
Same vendor: modelcontextprotocol
Same weakness: CWE-863