CVE-2026-48529
GitHub MCP Server: Lockdown mode singleton in HTTP server causes cross-user GraphQL client confusion
- Published
- Updated
- Reserved
- Assigned by
- GitHub_M
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.
Scores
| Scored by | CVSS | Score | Vector |
|---|---|---|---|
| GitHub_MCNA (assigner) | 3.1 | Medium6.0 | CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:C/C:L/I:L/A:L |
| NVDNVD · Deferred | 3.1 | Medium6.0 | CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:C/C:L/I:L/A:L |
- EPSS (exploitation in 30 days)
- 0.17% · top 94% of all CVEs (6 Nov 2026)
- CISA SSVC
- Exploitation: poc · Automatable: no · Technical impact: partial
The list uses the assigner's score when there is one, then CISA's, then NVD's: Medium 6.0.
Weakness
Affected products
- affected >= 0.22.0, < 1.1.2
Affected packages
From reviewed advisories of the GitHub Advisory Database.
- Gogithub.com/github/github-mcp-serverGHSA-pjp5-fpmr-3349 (opens in a new tab)
References (1)
- https://github.com/github/github-mcp-server/security/advisories/GHSA-pjp5-fpmr-3349 (opens in a new tab)x_refsource_CONFIRMexploit
Sources
The same CVE in the primary databases and aggregators, to check against.
- CVE.org record (opens in a new tab)
- CVE List JSON (GitHub) (opens in a new tab)
- NVD (opens in a new tab)
- FIRST EPSS (opens in a new tab)
- OSV.dev (opens in a new tab)
- GitHub Advisory GHSA-pjp5-fpmr-3349 (opens in a new tab)
- CIRCL Vulnerability-Lookup (opens in a new tab)
Badge for a README or a ticket
[](https://trackcve.app/cve/CVE-2026-48529)Record last updated .