CVE-2026-34742

Fixed in a distro release EPSS <1%CVSS 7.6

The Go MCP SDK used Go's standard encoding/json. Prior to version 1.4.0, the Model Context Protocol (MCP) Go SDK does not enable DNS rebinding protection by default for HTTP-based servers. When an HTTP-based MCP server is run on localhost without authentication with StreamableHTTPHandler or SSEHandler, a malicious website could exploit DNS rebinding to bypass same-origin policy restrictions and send requests to the local MCP server. This could allow an attacker to invoke tools or access resources exposed by the MCP server on behalf of the user in those limited circumstances. This issue has been patched in version 1.4.0.

Published 2026-04-02 · CVE record · OSV

Products: modelcontextprotocol go-sdk, Red Hat OpenShift Dev Spaces 3.28, Red Hat Migration Toolkit for Virtualization, Red Hat OpenShift Lightspeed, Red Hat OpenShift Serverless, Red Hat OpenShift AI (RHOAI)

Fixed upstream

Distro releases