CVE•Published 2026-07-29•Modified 2026-07-30•0 articles on news•5 live references•NVD data

CVE-2026-63118

Vulnerability data via NVD (ingested)

CVSS v3.1

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EPSS percentile

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Weaknesses (CWE)

CWE-346Origin Validation Error CWE-350Reliance on Reverse DNS Resolution for a Security-Critical Action

Description

MCP Ruby SDK is the official Ruby SDK for Model Context Protocol servers and clients. Prior to 0.23.0, MCP::Server::Transports::StreamableHTTPTransport in the mcp gem does not validate the HTTP Host or Origin request headers, which allows a malicious browser page to use DNS rebinding to reach a locally running MCP server and invoke exposed tools. This issue is fixed in version 0.23.0.

Timeline

Published 2026-07-29

Modified 2026-07-30

External references

NVD MITRE Exploit-DB GitHub PoC VulnCheck

Search for exposed instances

Shodan + Censys queries derived from NVD's CPE data. The vuln tag catches assets Shodan has explicitly linked to this CVE; the product / banner fingerprints find exposed instances even when the vuln tag was never applied (which is common).

Shodan · vuln tag0 hosts

vuln:CVE-2026-63118

Hosts Shodan has explicitly fingerprinted as vulnerable.

More intel sources (5)

Shodan report

vuln:CVE-2026-63118

Country / ASN / product breakdown for the vuln query.

Censys

vulnerabilities.cve_id: CVE-2026-63118

Censys host search filtered to this CVE id.

grep.app

CVE-2026-63118