CVE-2026-48529: GitHub GitHub-Mcp-Server

Medium severity, CVSS 6.0. EPSS: 0.2% chance of exploitation in the next 30 days.

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 products

• GitHub GitHub-Mcp-Server: from 0.22.0, before 1.1.2 (fixed in 1.1.2)

Published 2026-06-26. Last modified 2026-06-27.