Threat · curated 8 Aug 2026

CVE Record: CVE-2026-47427

First reported today cve.org

Coverage timeline

Single-source advisory — first reported, latest, and curated coincide.

Why it matters

CVE-2026-47427 lets an unauthenticated attacker fully crash GitHub's MCP Server with a single malformed JSON-RPC message, breaking the tool-calling backbone that AI agents rely on and making MCP infrastructure a direct availability target.

CVE-2026-47427 is a null pointer dereference denial-of-service in GitHub's official MCP Server (github-mcp-server) prior to version 1.1.0, where the CompletionsHandler in pkg/github/server.go accesses params.Ref without a nil check. A completion/complete JSON-RPC request with a missing or empty ref field triggers a Go runtime panic before any authentication, letting any unauthenticated client crash the server. The issue is fixed in version 1.1.0 (CVSS 7.5 HIGH).