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CVE-2026-34742

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

Published: Apr 2, 2026Updated: Apr 3, 2026 Sources: CVE List NVDCWE-1188
NVD MITRE
8.1CVSSHIGH
EPSS Score
0.4%
Top 66.6%
CISA KEV
Not in KEV
Exploits
No Known Exploits
Remediation
Patch Available

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 Vector Breakdown

AV:NAC:LPR:NUI:RS:UC:HI:HA:N
Exploitability
AV:NAttack Vector
Network
AC:LAttack Complexity
Low
PR:NPrivileges Required
None
UI:RUser Interaction
Required
Scope
S:UScope
Unchanged
Impact
C:HConfidentiality
High
I:HIntegrity
High
A:NAvailability
None
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Weaknesses

CWE-1188

Affected Products

go-sdkmodelcontextprotocol
Mixed
AI / ML / ai-agent-tooling
mcp go sdklfprojects
Mixed
AI / ML / notebook-mlops
modelcontextprotocoloss-projectAI / MLaka mcp, model context protocol
lfprojectsoss-projectAI / MLaka mlflow, valkey, model context protocol servers, mcp servers

Exploitability

Official Patch Available

References

https://github.com/modelcontextprotocol/go-sdk/security/advisories/GHSA-xw59-hvm2-8pj6
github.com
https://github.com/modelcontextprotocol/go-sdk/pull/760
github.com
https://github.com/modelcontextprotocol/go-sdk/commit/67bd3f2e2b53ce11a16db8d976cdb8ff1e986b6d
github.com
and 1 more references View all →

Timeline

Published
Apr 2, 2026
Last Updated
Apr 3, 2026

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