Description
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.
Details
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:H/A:L
Affected Packages
| Software | From version | Fixed in |
|---|---|---|
| github.com/modelcontextprotocol/go-sdk | — | — |
| mcp-go-sdk | — | 1.4.1 |
References
Similar Threats
- High CVE-2026-34742
- Unknown GO-2026-4770
- High GHSA-q382-vc8q-7jhj
- High CVE-2026-27896
Patch Gap Protection
Running software with known vulnerabilities?
BotEraser can help reduce exposure by blocking IPs associated with exploit activity — even before a patch is available.
Start Free →No credit card required · Results in minutes
ⓘ Data Notice: The information presented above has been compiled from publicly available internet sources. Boteraser aggregates this data solely for informational purposes and does not independently classify, evaluate, or endorse any findings about the vulnerabilities listed. The accuracy and completeness of this information is the sole responsibility of the original publishers. Boteraser and its operators accept no liability for any decisions made based on this data.