GitHub MCP Server – NULL Pointer Dereference Denial of Service (CVE-2026-47427)

Scope: GitHub MCP Server, Versions Prior to 1.1.0

Severity: High

A denial-of-service (DoS) vulnerability exists in the GitHub MCP Server due to a NULL pointer dereference flaw within the CompletenessHandler function in pkg/github/server.go. The function attempts to access params.Ref without verifying if the value is nil. An unauthenticated remote attacker can exploit this by transmitting a crafted JSON-RPC completion/complete request that intentionally omits or empties the ref field. Because this action triggers a Go runtime panic before any authentication or token validation occurs, an attacker requires no credentials to repeatedly crash the server. This can keep the service offline indefinitely, resulting in a complete denial of service for all legitimate users and dependent integrated systems. Organizations must upgrade the GitHub MCP Server to version 1.1.0 or later immediately. As supplementary defenses, administrators should deploy a reverse proxy or API gateway to validate incoming JSON-RPC messages, reject malformed requests before routing them to the server, and implement load balancing across multiple server instances to enhance architectural resilience.

The Uganda National CERT and Coordination Center (CERT.UG/CC) encourages users and administrators to review the NVD Record for CVE-2026-47427 and apply the necessary updates.