CVE-2026-34742

8.1 HIGH
Published: April 02, 2026 Modified: April 03, 2026
View on NVD

Description

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.

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CVSS v3.x Details

0.0 Low Medium High Critical 10.0
Vector String
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:N

References to Advisories, Solutions, and Tools

Patch Vendor Advisory Exploit Third Party Advisory
https://github.com/modelcontextprotocol/go-sdk/pull/760
Source: security-advisories@github.com
Issue Tracking Patch
https://github.com/modelcontextprotocol/go-sdk/releases/tag/v1.4.0
Source: security-advisories@github.com
Release Notes

4 reference(s) from NVD

Quick Stats

CVSS v3 Score
8.1 / 10.0
EPSS (Exploit Probability)
0.1%
17th percentile
Exploitation Status
Not in CISA KEV

Weaknesses (CWE)

Affected Vendors

lfprojects