Is CVE-2026-34742 actively exploited?

CVE-2026-34742 has no public evidence of in-the-wild exploitation as of 2026-04-03.

What is the CVSS score for CVE-2026-34742?

CVE-2026-34742 has a CVSS score of 7.6 (HIGH severity). Vector: CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:P/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X.

How do I patch CVE-2026-34742?

Patch guidance is available from lfprojects security advisories. CVEDatabase generates AI-assisted remediation guidance on demand for CVE-2026-34742.

Which products are affected by CVE-2026-34742?

1 product: lfprojects mcp go sdk.

Fix CVE-2026-34742 - HIGH lfprojects mcp go sdk

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.

CVSS Metrics

Vector: CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:P/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
Attack Vector: network
Complexity: low
Privileges: none
User Action: passive
Confidentiality: undefined
Integrity: undefined
Availability: undefined
Weaknesses: CWE-1188

Metadata

Primary Vendor: LFPROJECTS
Published: 4/2/2026
Last Modified: 4/3/2026
Source: NIST NVD
Note: Verify all details with official vendor sources before applying patches.

Affected Products

lfprojects : mcp_go_sdk

Remediation Guidance

Executive Summary

Cite this page

CVE-2026-34742. CVEDatabase.com. Retrieved 1 May 2026. https://cvedatabase.com/cve/CVE-2026-34742

View on NIST NVD

CVE-2026-34742 vulnerability