CVE-2026-48529

MEDIUM

GitHub MCP Server: Lockdown mode singleton in HTTP server causes cross-user GraphQL client confusion

Title source: cna
STIX 2.1

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.

References (1)

Core 1
Core References

Scores

CVSS v3 6.0
EPSS 0.0021
EPSS Percentile 10.6%
Attack Vector NETWORK
CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:C/C:L/I:L/A:L

CISA SSVC

Vulnrichment
Exploitation poc
Automatable no
Technical Impact partial

Details

CWE
CWE-284
Status published
Products (1)
github/github-mcp-server >= 0.22.0, < 1.1.2
Published Jun 26, 2026
Tracked Since Jun 26, 2026