CVE-2026-48529
GitHub MCP Server: Lockdown mode singleton in HTTP server causes cross-user GraphQL client confusion
Vexday Risk Score
10Low
SSVC decision (CISA)
Track
No exploitation signal → monitor
CVSS 6EPSS —KEV nãoPoC —Nuclei —Metasploit —Patch —
Lifecycle
26 Jun 2026Published on NVD
Recommendation: Monitor — no exploitation signal at the moment.
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.
CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:C/C:L/I:L/A:L
Affected products
github · github-mcp-serverWant to know if your infrastructure is exposed to this?
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