CVE-2026-33252
The Go MCP SDK used Go's standard encoding/json. Prior to version 1.4.1, the Go SDK's Streamable HTTP transport accepted browser-generated cross-site `POST` requests without validating the `Origin` header and without requiring `Content-Type: application/json`. In deployments without Authorization, especially stateless or sessionless configurations, this allows an arbitrary website to send MCP requests to a local server and potentially trigger tool execution. Version 1.4.1 contains a patch for the issue.
Published:Mar 23, 2026
Last Modified:Apr 15, 2026
EPS:Mar 23, 2026
EPSS Score:0.00007
CVSS Score:7.1
Affected Products
Vendor
Product
Action
Vendor
Lfprojects
Product
Mcp Go Sdk
Lfprojects
Mcp Go Sdk
Vendor
Modelcontextprotocol
Product
Go-sdk
Modelcontextprotocol
Go-sdk
Exploits
No exploit reference
Common Weakness Enumeration
Common Attack Pattern Enumeration and Classification (CAPEC)
Related CVEs
Common Vulnerability Scoring System
Attack Vector
Network
Adjacent
Local
Physical
Privileges Required
None
Low
High
User Interaction
None
Required
Scope
Unchanged
Changed
Confidentiality
None
Low
High
Integrity
None
Low
High
Availability
None
Low
High
