CVE-2026-347428.0HighCWE-1188

CVE-2026-34742: Model Context Protocol Go SDK: DNS Rebinding Protection Disabled by Default for Servers Running on Localhost

modelcontextprotocol · go-sdk

Vendor fix available · Affected: modelcontextprotocol go-sdk · Exploitation: unlikely (under 1%)

Not in CyberSIXT coverage yet: no article names this CVE. This page shows the public record.

0.5%probability of exploitation in the next 30 days

41st percentile

050100

Higher than 41% of scored CVEs

8.0HighCVSS 3.1

LowMediumHighCrit.

DescriptionCVE.org

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.

Affected products1

From the CVE record. A product or version that is not listed is unknown, not unaffected.

modelcontextprotocol · go-sdk< 1.4.0

On the Atlas

Every published CVE is on the CyberSIXT Atlas, grouped by weakness, vendor and month.

Open the Atlas

Exploitation: Unlikely (under 1%). EPSS under 1%, or no score yet.
CISA KEV: Not listed
Public check: No public nuclei template
Weakness: Initialization of a Resource with an Insecure Default · Misconfiguration and Insecure Design
Vendor: modelcontextprotocol
Published: April 2026
Band: Unlikely (under 1%), April 2026

CoverageNo articles yet

No CyberSIXT article names CVE-2026-34742 yet, so there is no coverage timeline, action brief or change log for it. Everything on this page comes from the public CVE record, CISA KEV, EPSS and the nuclei template index. Search the archive or see the CVEs in the news.