CVSS 3.1
6.5 mediumCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:H/A:NCVE-2026-33252
Medium (6.5) in lfprojects mcp go sdk. EPSS 0.2% chance of exploitation in the next 30 days. Fixed in github.com/modelcontextprotocol/go-sdk 1.4.1.
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.
Severity
- EPSS
- 0.2% chance of exploitation in the next 30 days; higher than 7% of CVEs (scores of 2026-10-31)
- CWE
- CWE-352
- Published
- Modified
- Record from
- the NVD, synced
Affected
- lfprojects:mcp_go_sdk
Packages (OSV)
| Advisory | Ecosystem | Package | Affected | Fixed in |
|---|---|---|---|---|
| GHSA-89xv-2j6f-qhc8 | Go | github.com/modelcontextprotocol/go-sdk | <1.4.1 | 1.4.1 |
| GO-2026-4773 | Go | github.com/modelcontextprotocol/go-sdk | <1.4.1 | 1.4.1 |