CVE-2026-47427
Medium
Elevated severity or exploit probability.
CVSS base
7.5
HIGH
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
EPSS — probability of exploitation (30 days)
0.8%
53.8th percentile
CISA KEV
Not listed
Weakness / dates
CWE-476
Published 2026-07-28 · modified 2026-08-08
Description
GitHub MCP Server is GitHub's official MCP Server. Prior to 1.1.0, the CompletionsHandler function in pkg/github/server.go accesses params.Ref without first checking whether it is nil, so a completion/complete request with a missing or empty ref field triggers a nil pointer dereference and a Go runtime panic; because the crash occurs before any authentication or token validation, any unauthenticated client able to send JSON-RPC messages can crash the server, resulting in a complete denial of service. This issue is fixed in version 1.1.0.
Affected
References
- https://github.com/github/github-mcp-server/commit/c88d2ecdd3bb07f7bdd75296e3ee676febf14f58
- https://github.com/github/github-mcp-server/pull/2502
- https://github.com/github/github-mcp-server/releases/tag/v1.1.0
- exploit https://github.com/github/github-mcp-server/security/advisories/GHSA-w4q6-qw23-4rg7
- exploit https://github.com/github/github-mcp-server/security/advisories/GHSA-w4q6-qw23-4rg7