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CVE-2026-44430

4.0 · MEDIUM

The MCP Registry provides MCP clients with a list of MCP servers, like an app store for MCP servers.

Published May 14, 2026CWE-918EPSS 0.29%

Overview

CVE-2026-44430 is a medium-severity vulnerability. It was published on May 14, 2026 and has a CVSS 3.1 base score of 4.0 (MEDIUM).

This vulnerability has a CVSS 3.1 base score of 4.0, rated MEDIUM. It can be exploited remotely over the network. No authentication or special privileges are required for exploitation.

Technical description

The MCP Registry provides MCP clients with a list of MCP servers, like an app store for MCP servers. Prior to 1.7.7, the Registry's HTTP-based namespace verification (POST /v0/auth/http, POST /v0.1/auth/http) uses safeDialContext (internal/api/handlers/v0/auth/http.go:67-110) to refuse dialling private/internal addresses when fetching the well-known public-key file from a publisher-supplied domain. The blocklist (isBlockedIP, lines 125-133) relies entirely on Go stdlib's IsLoopback / IsPrivate / IsLinkLocalUnicast / IsMulticast / IsUnspecified plus a manual CGNAT range. None of these cover IPv6 6to4 (2002::/16), NAT64 (64:ff9b::/96 and 64:ff9b:1::/48 per RFC 8215), or deprecated site-local (fec0::/10) — all of which encode arbitrary IPv4 in the address bits and tunnel to RFC1918 / cloud-metadata services on dual-stack / NAT64-enabled hosts. This vulnerability is fixed in 1.7.7.

Remediation

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

References

GitHubgithub.com/modelcontextprotocol/registry/security/advisories/GHSA-r48c-v28r-pf6vGitHubgithub.com/modelcontextprotocol/registry/security/advisories/GHSA-r48c-v28r-pf6v

How CyberStrike helps

Frequently asked questions

What is CVE-2026-44430?

CVE-2026-44430 is a medium-severity vulnerability. It was published on May 14, 2026 and has a CVSS 3.1 base score of 4.0 (MEDIUM).

How severe is CVE-2026-44430?

This vulnerability has a CVSS 3.1 base score of 4.0, rated MEDIUM. It can be exploited remotely over the network. No authentication or special privileges are required for exploitation.

How do I fix or remediate CVE-2026-44430?

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

How can CyberStrike help with CVE-2026-44430?

CyberStrike is an open-source, AI-augmented pentesting engine. Rather than flag a version number, it tests whether an issue like CVE-2026-44430 is actually reachable in your own applications and APIs, then verifies each finding before reporting it. That tells you if the weakness is a real, exploitable risk in your environment or a false positive you can safely deprioritize.

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