CVE-2026-44430
- Source
- https://cve.org/CVERecord?id=CVE-2026-44430
- Import Source
- https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-44430.json
- JSON Data
- https://api.osv.dev/v1/vulns/CVE-2026-44430
- Aliases
- Related
- Published
- 2026-05-14T21:02:40.738Z
- Modified
- 2026-07-15T01:49:13.645961694Z
- Severity
-
- 6.3 (Medium) CVSS_V4 - 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 CVSS Calculator
- Summary
- MCP Registry: Unauthenticated SSRF: HTTP namespace verification dials 6to4 / NAT64 / site-local IPv6 addresses, bypassing private-address allowlist
- Details
-
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.
- Database specific
{ "cna_assigner": "GitHub_M", "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/44xxx/CVE-2026-44430.json", "cwe_ids": [ "CWE-918" ] }- References
Affected packages
Git / github.com/modelcontextprotocol/registry
Affected ranges
- Type
- GIT
- Repo
- https://github.com/modelcontextprotocol/registry
- Events
-
Introduced0 Unknown introduced commit / All previous commits are affectedFixed
- Database specific
{ "cpe": "cpe:2.3:a:lfprojects:mcp_registry:*:*:*:*:*:*:*:*", "source": [ "AFFECTED_FIELD", "CPE_RANGE" ], "extracted_events": [ { "introduced": "0" }, { "fixed": "1.7.7" } ] }