CVE-2026-48529— GitHub MCP Server: Lockdown mode singleton in HTTP server causes cross-user GraphQL client confusion
Quick assessment
Affected
github github-mcp-server
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.
GitHub GitHub MCP Server是美国GitHub公司开源的一个Model Context Protocol（模型上下文协议）服务器实现。 GitHub MCP Server 0.22.0版本至1.1.2之前版本存在权限许可和访问控制问题漏洞，该漏洞源于RepoAccessCache实现为进程全局单例，使用第一个通过身份验证用户的GraphQL客户端初始化，后续所有请求均使用该用户的凭据，可能导致权限许可和访问控制问题。
Possible ATT&CK Techniques 1 AI
T1078 · Valid AccountsAffected Version Matrix 1
| Vendor | Product | Version Range | Status |
|---|---|---|---|
| github | github-mcp-server | >= 0.22.0, < 1.1.2 |
affected |
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I. Basic Information for CVE-2026-48529
Vulnerability Information
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Vulnerability Title
GitHub MCP Server: Lockdown mode singleton in HTTP server causes cross-user GraphQL client confusion
Source: CVE Program / CVE List V5
Vulnerability Description
GitHub MCP Server is GitHub's official MCP Server. From 0.22.0 until 1.1.2, when running in HTTP mode with --lockdown-mode enabled, the RepoAccessCache is implemented as a process-global singleton initialized with the first authenticated user's GraphQL client. All subsequent requests from different users share this singleton and their lockdown-related GraphQL queries are executed using the first user's credentials. The singleton is never updated to reflect later users' tokens. This vulnerability is fixed in 1.1.2.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:C/C:L/I:L/A:L
Source: CVE Program / CVE List V5
Vulnerability Type
访问控制不恰当
Source: CVE Program / CVE List V5
Vulnerability Title
GitHub MCP Server 权限许可和访问控制问题漏洞
Source: CNNVD (China National Vulnerability Database)
Vulnerability Description
GitHub GitHub MCP Server是美国GitHub公司开源的一个Model Context Protocol（模型上下文协议）服务器实现。 GitHub MCP Server 0.22.0版本至1.1.2之前版本存在权限许可和访问控制问题漏洞，该漏洞源于RepoAccessCache实现为进程全局单例，使用第一个通过身份验证用户的GraphQL客户端初始化，后续所有请求均使用该用户的凭据，可能导致权限许可和访问控制问题。
Source: CNNVD (China National Vulnerability Database)
CVSS Information
N/A
Source: CNNVD (China National Vulnerability Database)
Vulnerability Type
N/A
Source: CNNVD (China National Vulnerability Database)
Affected Products
| Vendor | Product | Affected Versions | CPE | Subscribe |
|---|---|---|---|---|
| github | github-mcp-server | >= 0.22.0, < 1.1.2 | - |
|
II. Public POCs for CVE-2026-48529
| # | POC Description | Source Link | Shenlong Link |
|---|
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Vendor Advisories for CVE-2026-48529 (1)
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