CVE-2026-48529
GitHub MCP Server: Lockdown mode singleton in HTTP server causes cross-user GraphQL client confusion
Description
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.
No summary for this CVE yet.
CVSS Vector Breakdown
Exploitability
AV:NAttack VectorNetwork
AC:HAttack ComplexityHigh
PR:LPrivileges RequiredLow
UI:NUser InteractionNone
Scope
S:CScopeChanged
Impact
C:LConfidentialityLow
I:LIntegrityLow
A:LAvailabilityLow
Weaknesses
Affected Products
github
commercial·US
Exploitability
No known exploits, KEV entries, or remediation guidance available for this vulnerability yet.
References
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