GitHub MCP Server: Nil Pointer Dereference DoS in completion/complete Handler

{
  "id": "bfe8d9f342ca31c2f34d6192310d60e1c3aa26b426e19d6c1fc1b3e329b2fe5d",
  "url": "https://osv.dev/vulnerability/CVE-2026-47427",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "GitHub MCP Server: Nil Pointer Dereference DoS in completion/complete Handler",
    "summary": "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.",
    "evidence": "osv:CVE-2026-47427",
    "products": [],
    "severity": "high",
    "structured": {
      "id": "CVE-2026-47427",
      "aliases": [
        "CVE-2026-47427",
        "GHSA-w4q6-qw23-4rg7",
        "GO-2026-6118"
      ],
      "metrics": [
        {
          "type": "CVSS_V3",
          "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H"
        }
      ],
      "affected": [
        {
          "ranges": [
            {
              "repo": "https://github.com/github/github-mcp-server",
              "type": "GIT",
              "events": [
                {
                  "introduced": "0"
                },
                {
                  "fixed": "c5be4b09c2e26e9c6adbc936b5fc661306852ebf"
                },
                {
                  "fixed": "c88d2ecdd3bb07f7bdd75296e3ee676febf14f58"
                }
              ],
              "database_specific": {
                "extracted_events": [
                  {
                    "cpe": "cpe:2.3:a:github:mcp_server:*:*:*:*:*:*:*:*",
                    "range": [
                      {
                        "introduced": "0"
                      },
                      {
                        "fixed": "1.1.0"
                      }
                    ],
                    "source": "CPE_RANGE"
                  },
                  {
                    "range": [
                      {
                        "fixed": "c88d2ecdd3bb07f7bdd75296e3ee676febf14f58"
                      }
                    ],
                    "source": "REFERENCES_COMMIT"
                  },
                  {
                    "range": [
                      {
                        "fixed": "c5be4b09c2e26e9c6adbc936b5fc661306852ebf"
                      }
                    ],
                    "source": "REFERENCES_TAG",
                    "original_tag": "v1.1.0"
                  }
                ]
              }
            }
          ],
          "versions": [
            "v1.0.5",
            "v1.0.4",
            "v1.0.3",
            "v1.0.2",
            "v1.0.1",
            "v1.0.0",
            "v0.33.1",
            "v0.33.0",
            "v0.32.0",
            "v0.31.0",
            "v0.30.3",
            "v0.30.2",
            "v0.30.1",
            "v0.30.0",
            "v0.29.0",
            "v0.28.1",
            "v0.28.0",
            "v0.27.0",
            "v0.26.3",
            "v0.26.2",
            "v0.26.1",
            "v0.26.0",
            "v0.25.0",
            "v0.24.1",
            "v0.24.0",
            "v0.22.0",
            "v0.23.0",
            "v0.21.0",
            "v0.20.2",
            "v0.20.1",
            "v0.20.0",
            "v0.19.1",
            "v0.19.0",
            "v0.18.0",
            "v0.17.1",
            "v0.17.0",
            "v0.16.0",
            "v0.15.0",
            "v0.13.0",
            "v0.14.0",
            "v0.12.1",
            "v0.12.0",
            "v0.11.0",
            "v0.10.0",
            "v0.9.1",
            "v0.9.0",
            "v0.8.0",
            "v0.7.0",
            "v0.6.0",
            "v0.5.0",
            "v0.4.0",
            "v0.3.0",
            "v0.2.1",
            "v0.2.0",
            "v0.1.1-release-validation",
            "v0.1.1",
            "v0.1.0",
            "v0.1.0-rc.3",
            "v0.1.0-rc.2",
            "v0.1.0-rc.1"
          ],
          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-47427.json"
          }
        }
      ],
      "modified": "2026-10-28T02:30:20.556659621Z",
      "provider": "osv",
      "references": [
        "https://github.com/github/github-mcp-server/releases/tag/v1.1.0",
        "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/47xxx/CVE-2026-47427.json",
        "https://github.com/github/github-mcp-server/security/advisories/GHSA-w4q6-qw23-4rg7",
        "https://nvd.nist.gov/vuln/detail/CVE-2026-47427",
        "https://github.com/github/github-mcp-server/commit/c88d2ecdd3bb07f7bdd75296e3ee676febf14f58",
        "https://github.com/github/github-mcp-server/pull/2502"
      ],
      "provider_metadata": {
        "cwe_ids": [
          "CWE-476"
        ],
        "cna_assigner": "GitHub_M",
        "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/47xxx/CVE-2026-47427.json"
      }
    },
    "related_cves": [
      {
        "value": "CVE-2026-47427",
        "evidence": "/id"
      }
    ],
    "security_relevant": true,
    "severity_evidence": "/severity/0/score"
  },
  "source_id": "core-osv",
  "document_id": 486934,
  "published_at": "2026-07-28T15:32:27.294+00:00"
}