TI-2026-34990 Aliases CVE-2026-47427 GHSA-w4q6-qw23-4rg7

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

HIGH 72CWE-476Published 2026-07-28 · Updated 2026-07-28

Key facts

Attack vector: Network
Privileges required: None
User interaction: None
Attack complexity: Low
Impact type: Denial of service
Confidentiality · integrity · availability: None · None · High
Fix status: Fixed

Attack profile from CVSS 3.1 · CNA. Fix status from CNA and GitHub. Impact type from CWE-476.

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.

Why it matters now

Exploitation Proof of concept CISA SSVC · not in CISA KEV

EPSS 0.00772 55th percentileScored 2026-11-07

Public exploit Yes 1 exploit referenceTagged by NVD

Fix Fixed github-mcp-server (github): 1.1.0github.com/github/github-mcp-server (Go): 1.1.0

SSVC decision points

CISA ADP · SSVC 2.0.3

Exploitation: Poc
Automatable: Yes
Technical impact: Partial

The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.

Affected products

Vendor	Product	Affected versions	Fixed in	Status	Source
GitHub	github-mcp-server	before 1.1.0	1.1.0	Patch available	CNA
—	github.com/github/github-mcp-server (Go)	before 1.1.0	1.1.0	Patch available	GHSA-w4q6-qw23-4rg7

github-mcp-server VendorGitHub Affected before 1.1.0 Fixed in 1.1.0 Patch available CNA
github.com/github/github-mcp-server (Go) Vendor— Affected before 1.1.0 Fixed in 1.1.0 Patch available GHSA-w4q6-qw23-4rg7

CPE configurations NVD · 1

CPE	Versions	Role	Vendor
cpe:2.3:a:github:mcp_server::::::::	before 1.1.0	Vulnerable	GitHub

cpe:2.3:a:github:mcp_server:*:*:*:*:*:*:*:* Versions before 1.1.0 Vulnerable ·GitHub

Remediation

Fix · CNA github-mcp-server (github) Fixed in 1.1.0
Fix · GHSA-w4q6-qw23-4rg7 github.com/github/github-mcp-server (Go) Fixed in 1.1.0 Advisory →

Timeline

2026-10-02 Threatist record created from CVE-2026-47427
2026-10-03 Alias added: GHSA-w4q6-qw23-4rg7

References

Exploit 1

https://github.com/github/github-mcp-server/security/advisories/GHSA-w4q6-qw23-4rg7

Patch 2

Other 2

Sources

This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences