# CVE-2026-48529: GitHub MCP Server: Lockdown mode singleton in HTTP server causes cross-user GraphQL client confusion

> CVE-2026-48529: GitHub MCP Server: Lockdown mode singleton in HTTP server causes cross-user GraphQL client confusion. CVSS 6.0 (CVSS 3.1).

Canonical: https://rewindex.com/cve/CVE-2026-48529
Last updated: 2026-10-25T17:10:00Z

- Published: 2026-06-26 16:33 UTC · Updated: 2026-10-25 17:10 UTC · Assigner: GitHub\_M
- CVSS: 6.0 (CVSS 3.1) · Severity: Medium · Vector: CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:C/C:L/I:L/A:L
- EPSS: 0.21%, 10th percentile (scored 2026-10-25)
- CISA KEV: no
- CWE: CWE-284

## 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.

## Affected vendors and products

- github: github-mcp-server

## Tracked companies

- [GitHub](https://rewindex.com/company/github.md)

## References

- [CVE record on cve.org](https://www.cve.org/CVERecord?id=CVE-2026-48529)
- [NVD entry](https://nvd.nist.gov/vuln/detail/CVE-2026-48529)
- [https://github.com/github/github-mcp-server/security/advisories/GHSA-pjp5-fpmr-3349](https://github.com/github/github-mcp-server/security/advisories/GHSA-pjp5-fpmr-3349)

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_Sources: CVE records from the CVE Program (cve.org). CVE® is a registered trademark of The MITRE Corporation. (https://www.cve.org/) This product uses data from the NVD API but is not endorsed or certified by the NVD. (https://nvd.nist.gov/) Known Exploited Vulnerabilities catalog from CISA. (https://www.cisa.gov/known-exploited-vulnerabilities-catalog) EPSS scores from FIRST (Exploit Prediction Scoring System). (https://www.first.org/epss/)_


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Canonical: https://rewindex.com/cve/CVE-2026-48529 · Markdown: https://rewindex.com/cve/CVE-2026-48529.md · JSON: https://rewindex.com/api/v1/cves/CVE-2026-48529 · Data licensed CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/) · Generated 2026-10-26T03:10:16.358Z