CVE-2026-48529
GitHub MCP Server: Lockdown mode singleton in HTTP server causes cross-user GraphQL client confusion
CVSS Score
6.0
EPSS Score
0.0%
EPSS Percentile
0th
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.
| CWE | CWE-284 |
| Vendor | github |
| Product | github-mcp-server |
| Ecosystems | |
| Industries | Technology |
| Published | Jun 26, 2026 |
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CVSS v3 Breakdown
CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:C/C:L/I:L/A:L Attack Vector
Network
Attack Complexity
High
Privileges Required
Low
User Interaction
None
Scope
Changed
Confidentiality
Low
Integrity
Low
Availability
Low
Affected Versions
github / github-mcp-server
>= 0.22.0, < 1.1.2