CVE-2026-48529 — GitHub MCP Server: Lockdown mode singleton in HTTP server causes cross-user GraphQL client confusion
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 proce…
Published: 2026-06-26 · CVSS: 6.0 · CVSS 3.1
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 · Revision 8b16575c39f1e1810c5e863010da073d2d3285e7