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.
Attack Parameters
Attack Vector
Network
Can be exploited remotely
Attack Complexity
Low
Easy to exploit
Privileges Required
None
No privileges needed
User Interaction
None
No user interaction needed
Impact Assessment
Confidentiality
None
No data leak
Integrity
None
No data modification
Availability
High
Complete denial of service
CVSS Vector v3.1
Weakness Type (CWE)
References 4
https://github.com/github/github-mcp-server/commit/c88d2ecdd3bb07f7bdd75296e3ee…
security-advisories@github.com
https://github.com/github/github-mcp-server/pull/2502
security-advisories@github.com
https://github.com/github/github-mcp-server/releases/tag/v1.1.0
security-advisories@github.com
https://github.com/github/github-mcp-server/security/advisories/GHSA-w4q6-qw23-…
security-advisories@github.com