High severity · published Jul 28, 2026
CVE-2026-47427
GitHub MCP Server: Nil Pointer Dereference DoS in completion/complete Handler
7.5
CVSS
0.8%
EPSS
No
On KEV
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.
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Attack vector
Network
Complexity
Low
Privileges
None
User interaction
None
Confidentiality
None
Integrity
None
Availability
High
Scope
Unchanged
Exploitation
Is it being used?
Exploit prediction (EPSS)0.8% · higher than 56% of CVEs
Exploited in the wildNo evidence yet
CISA KEVNot listed
Ransomware campaign useNot known
Affected products
Which versions
GI
github-mcp-server · github
< 1.1.0 · source: vendor
MS
Mcp Server · Github
before 1.1.0 · source: NVD
References
NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-47427
CVE.org
https://www.cve.org/CVERecord?id=CVE-2026-47427
Patch
https://github.com/github/github-mcp-server/commit/c88d2ecdd3bb07f7bdd75296e3ee676febf14f58
Issue Tracking
https://github.com/github/github-mcp-server/pull/2502
Release Notes
https://github.com/github/github-mcp-server/releases/tag/v1.1.0
Exploit
https://github.com/github/github-mcp-server/security/advisories/GHSA-w4q6-qw23-4rg7
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