CVEvulnerability

CVE-2026-44430

6.3 MEDIUM Published 2026-05-14 Modified 2026-10-26 Official page ↗
Status
Modified
Published
2026-05-14
Last modified
2026-10-26
Assigner
[email protected]
CVSS 4.0 ([email protected])
6.3 MEDIUM — CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:N/SC:L/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
CVSS 3.1 ([email protected])
4.0 MEDIUM — CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:N/I:L/A:N
Weaknesses
CWE-918

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.

Affected configurations

• lfprojects mcp registry (< 1.7.7)

Related

Weakness · CWE (1)

  • CWE-918 Server-Side Request Forgery weakness

References