CVE-2026-34742 is a high-severity DNS rebinding vulnerability affecting lfprojects Go MCP SDK versions prior to 1.4.0. This flaw allows a malicious website to bypass same-origin policy by exploiting HTTP-based MCP servers running on localhost without authentication, enabling an attacker to send requests to the local server. With a CVSS score of 8.1, the vulnerability has low attack complexity but requires user interaction, potentially leading to high impact on confidentiality and integrity by allowing attackers to invoke tools or access resources on behalf of the user. There is currently no evidence of active exploitation, nor are there public exploit codes available in Metasploit, Nuclei, or ExploitDB, with minimal community discussion. The issue has been patched in version 1.4.0.
| Vendor | Product | Version(s) | CPE |
|---|---|---|---|
< 1.4.0CPE matchmatch criteria | cpe:2.3:a:lfprojects:mcp_go_sdk:*:*:*:*:*:*:*:* |
CVSS version used by this source: 4.0
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
The average CVE in this peer group has 0.0 Twitter, 0.1 Reddit, 0.2 Bluesky, 0.1 Mastodon, and 0.2 GitHub mentions.
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The average CVE in this peer group has 0.3 InfoSec Media, 0.0 Vendor Blog, and 0.1 Security Researcher mentions.