CVE-2026-48529
GitHub MCP Server: Lockdown mode singleton in HTTP server causes cross-user GraphQL client confusion
MEDIUM 6.0EPSS 0.2%
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.
- Affected
- github · github-mcp-server
- CVSS v3.1 GITHUB
- 6.0 MEDIUM
CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:C/C:L/I:L/A:L - EPSS
- 0.21% chance of exploitation in the next 30 days, 10th percentile
- Published
- 2026-06-26
- Updated
- 2026-06-27