High 7.6Published Apr 2, 2026

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

Updated under an hour ago (Oct 27, 2026, 9:23 PM ET)

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It affects modelcontextprotocol go-sdk and 6 other products. Add what you run to find out whether that includes you.

No exploitation reported and no EPSS estimate yet.

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Every CVE for modelcontextprotocol go-sdk

Exploited in the last 30 days

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: 7.6 HIGH (v4.0, CNA)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
Weakness (CWE): CWE-1188
Known exploited: Not in CISA's KEV catalog
EPSS (exploitation in the next 30 days): Not loaded for this CVE
Assigned by: GitHub_M
NVD analysis: Modified
Record last updated: Jul 14, 2026
First seen by InfoSec Signals: Oct 9, 2026

Affected products

Affected products

modelcontextprotocol go-sdk modelcontextprotocol:go_sdk (from the name)	before 1.4.0	CNA record
Red Hat Red Hat OpenShift Dev Spaces 3.28 redhat:openshift_devspaces	from 1779829736 not affected	CISA ADP
Red Hat Migration Toolkit for Virtualization redhat:migration_toolkit_virtualization	2	CISA ADP
Red Hat OpenShift Lightspeed redhat:openshift_lightspeed	Versions not stated	CISA ADP
Red Hat OpenShift Serverless redhat:serverless	1	CISA ADP
Red Hat Red Hat OpenShift AI (RHOAI) redhat:openshift_ai	Versions not stated	CISA ADP
lfprojects mcp_go_sdk lfprojects:mcp_go_sdk	before 1.4.0	NVD

References

References

https://github.com/modelcontextprotocol/go-sdk/security/advisories/GHSA-xw59-hvm2-8pj6	x-refsource-confirm, vendor-advisory
https://github.com/modelcontextprotocol/go-sdk/pull/760	x-refsource-misc, issue-tracking, patch
https://github.com/modelcontextprotocol/go-sdk/commit/67bd3f2e2b53ce11a16db8d976cdb8ff1e986b6d	x-refsource-misc, patch
https://github.com/modelcontextprotocol/go-sdk/releases/tag/v1.4.0	x-refsource-misc, release-notes
https://access.redhat.com/errata/RHSA-2026:21772
https://access.redhat.com/security/cve/CVE-2026-34742
https://bugzilla.redhat.com/show_bug.cgi?id=2454608
https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-34742.json

The CVE record on cve.org NVD's entry

The CVE record is authoritative. Products marked “from the name” were identified from the CNA's free-text names, not a CPE, and are matched less certainly. This product uses the NVD API but is not endorsed or certified by the NVD.