{"id":"CVE-2026-48529","aliases":["GHSA-pjp5-fpmr-3349","GO-2026-5779"],"url":"https://o3.security/vulnerability/CVE-2026-48529","summary":"GitHub MCP Server: Lockdown mode singleton in HTTP server causes cross-user GraphQL client confusion","details":"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.","published":"2026-06-26T16:33:32.688Z","modified":"2026-08-12T03:51:08.704225930Z","cvss":{"score":6,"severity":"MEDIUM","vector":"CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:C/C:L/I:L/A:L"},"epss":{"score":0.00205,"percentile":0.10678,"asOf":"2026-09-13"},"cisaKev":null,"exploitsKnown":0,"affectedPackages":[{"ecosystem":"Go","name":"github.com/github/github-mcp-server","fixedVersion":"1.1.2"}],"fix":null,"references":[{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/48xxx/CVE-2026-48529.json"},{"type":"ADVISORY","url":"https://github.com/github/github-mcp-server/security/advisories/GHSA-pjp5-fpmr-3349"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-48529"}],"provenance":{"sources":["OSV.dev","FIRST.org (EPSS)"],"lastVerified":"2026-08-12T03:51:08.704225930Z"}}