Vulnerability advisory
CVE-2026-47427
GitHub MCP Server: Nil Pointer Dereference DoS in completion/complete Handler
Also known as GHSA-w4q6-qw23-4rg7GO-2026-6118
Severity
- CVSS 3.x
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Affected versions
Repository
| Affected commits | Fixed by commit |
|---|---|
| GIT github.com/github/github-mcp-server ↗ | |
| All commits before c5be4b09c2e26e9c6adbc936b5fc661306852ebf | c5be4b09c2e26e9c6adbc936b5fc661306852ebf |
| Not specified | c88d2ecdd3bb07f7bdd75296e3ee676febf14f58 |
Also listed as affected (60)
| |
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.
References
- Webgithub.com/github/github-mcp-server/releases/tag/v1.1.0 ↗
- Advisorygithub.com/CVEProject/cvelistV5/tree/main/cves/2026/47xxx/CVE-2026-47427.json ↗
- Advisorygithub.com/github/github-mcp-server/security/advisories/GHSA-w4q6-qw23-4rg7 ↗
- Advisorynvd.nist.gov/vuln/detail/CVE-2026-47427 ↗
- Fixgithub.com/github/github-mcp-server/commit/c88d2ecdd3bb07f7bdd75296e3ee676febf14f58 ↗
- Fixgithub.com/github/github-mcp-server/pull/2502 ↗