PT-2026-29672 · Unknown · Go Mcp Sdk

Maciej-Kisiel · CVE-2026-34742 · Published 2026-04-01 · Updated 2026-07-30

Positive Technologies (AI Summary)

CVSS v3.1

8.1

High

Base vector

AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:N

Name of the Vulnerable Software and Affected Versions Go MCP SDK versions prior to 1.4.0

Description The Go MCP SDK, utilizing Go's standard encoding/json, did not enable DNS rebinding protection by default for HTTP-based servers prior to version 1.4.0. When an HTTP-based MCP server was run on localhost without authentication using 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.

Recommendations Update to version 1.4.0 or later.

Exploit

Fix

Weakness Enumeration

CWE-1188

Related Identifiers

CLEANSTART-2026-LO26058

CVE-2026-34742

GHSA-XW59-HVM2-8PJ6

GO-2026-5771

OPENSUSE-SU-2026:21483-1

Affected Products

Go Mcp Sdk

References · 1778

• 🔥 https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/34xxx/CVE-2026-34742.json · Exploit
• https://github.com/modelcontextprotocol/go-sdk/security/advisories/GHSA-xw59-hvm2-8pj6 · Vendor Advisory
• https://github.com/modelcontextprotocol/go-sdk/pull/760 · Patch
• https://github.com/modelcontextprotocol/go-sdk/commit/67bd3f2e2b53ce11a16db8d976cdb8ff1e986b6d · Patch
• https://nvd.nist.gov/vuln/detail/CVE-2026-1229 · Security Note
• https://osv.dev/vulnerability/CVE-2026-34742 · Vendor Advisory
• https://nvd.nist.gov/vuln/detail/CVE-2026-34742 · Security Note
• https://nvd.nist.gov/vuln/detail/CVE-2026-27896 · Security Note
• https://nvd.nist.gov/vuln/detail/CVE-2026-33762 · Security Note
• https://osv.dev/vulnerability/GHSA-xw59-hvm2-8pj6 · Vendor Advisory
• https://osv.dev/vulnerability/CLEANSTART-2026-LO26058 · Vendor Advisory
• https://osv.dev/vulnerability/GO-2026-5771 · Vendor Advisory
• https://nvd.nist.gov/vuln/detail/CVE-2026-25934 · Security Note
• https://access.redhat.com/errata/RHSA-2026:21772 · Vendor Advisory
• https://nvd.nist.gov/vuln/detail/CVE-2026-33252 · Security Note