CVE-2026-54450

Summary ToolHive's hand-rolled private/reserved-IP SSRF guard (networking.IsPrivateIP in pkg/networking/utilities.go) does not recognize the IPv6 NAT64 address ranges — the well-known prefix 64:ff9b::/96 (RFC 6052) and the RFC 8215 local-use prefix 64:ff9b:1::/48. As a result, an address such as 64:ff9b:1::a9fe:a9fe — the NAT64 encoding of the link-local cloud metadata address 169.254.169.254 — is classified as a public, global-unicast address and the connection is allowed. On any ToolHive deployment that sits behind a NAT64/DNS64 gateway (the default networking stack in IPv6-only Kubernetes clusters and several IPv6-only cloud environments), an attacker who controls a URL that reaches this guard can have ToolHive attempt connections to internal/link-local addresses that the guard is meant to block, bypassing the SSRF protection. In practice the effect is a blind internal-reachability probe rather than metadata-credential theft (the only fully attacker-controlled path is HTTPS-only with TLS verification and does not reflect responses) — see Impact. The most direct attacker-controlled entry point is the embedded OAuth authorization server's Client ID Metadata Document (CIMD) fetcher: an external OAuth client presents client_id=https://<attacker-domain>/path, and CIMDStorageDecorator.GetClient fetches that URL through the same guard. The same IsPrivateIP table is also shared by the protectedDialerControl HTTP clients (registry, OIDC discovery, token introspection) and the skills git-clone host check (pkg/skills/gitresolver), though those destinations are operator-/user-configured rather than attacker-controlled. (Note: the webhook client is *not* affected — it enforces only the HTTPS scheme via ValidatingTransport and performs no IP-based check.) Details pkg/networking/utilities.go builds a privateIPBlocks table and IsPrivateIP: func init() { for _, cidr := range []string{ "127.0.0.0/8", "10.0.0.0/8", "172.16.0.0/12", "192.168.0.0/16", "169.254.0.0/16", "::1/128"

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