{"id":"CVE-2026-54450","state":"PUBLISHED","title":"ToolHive: SSRF guard misses IPv6 NAT64 ranges (64:ff9b::/96, 64:ff9b:1::/48), allowing metadata/internal access behind a NAT64 gateway","description":"ToolHive is a utility designed to simplify the deployment and management of Model Context Protocol (MCP) servers. Prior to 0.29.1, networking.IsPrivateIP in pkg/networking/utilities.go omits the IPv6 NAT64 prefixes 64:ff9b::/96 and 64:ff9b:1::/48, so NAT64 addresses embedding private, loopback, or link-local IPv4 targets are classified as public and allowed. The most direct attacker-controlled path begins when an external OAuth client supplies a client_id URL that CIMDStorageDecorator.GetClient routes through FetchClientMetadataDocument in pkg/oauthproto/cimd/fetch.go; protectedDialerControl in pkg/networking/http_client.go and validateHost in pkg/skills/gitresolver/reference.go share the defective classification but use operator-controlled or user-controlled destinations. On a ToolHive host behind a NAT64/DNS64 gateway, the gateway translates an allowed address such as 64:ff9b:1::a9fe:a9fe to 169.254.169.254, permitting blind probing of internal TCP or TLS reachability. The attacker-controlled CIMD path requires HTTPS, verifies certificates, and does not reflect response bodies, so the established impact is an internal reachability oracle rather than metadata credential exfiltration; the webhook client is not affected because it does not use this IP guard. This issue is fixed in version 0.29.1.","publishedAt":"2026-09-15T15:47:39.377Z","updatedAt":"2026-09-15T16:13:16.652Z","severity":{"score":2.9,"label":"Low","version":"4.0","vector":"CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N/E:P","source":"GitHub_M"},"assigner":"GitHub_M","products":["stacklok toolhive"],"affected":[{"vendor":"stacklok","product":"toolhive","versions":[{"version":"< 0.29.1","status":"affected"}]}],"references":["https://github.com/stacklok/toolhive/security/advisories/GHSA-pph6-vfjv-vpjw","https://github.com/stacklok/toolhive/commit/26912af453d2040787983dbc9ab93a9019ec0468","https://github.com/stacklok/toolhive/releases/tag/v0.29.1"],"weaknesses":["CWE-918"],"ingestedAt":"2026-10-29T20:12:24.861Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/54xxx/CVE-2026-54450.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-54450","state":"PUBLISHED","datePublished":"2026-09-15T15:47:39.377Z","dateUpdated":"2026-09-15T16:13:16.652Z","assignerShortName":"GitHub_M","assignerOrgId":"a0819718-46f1-4df5-94e2-005712e83aaa","dateReserved":"2026-06-15T15:30:40.318Z"},"containers":{"cna":{"title":"ToolHive: SSRF guard misses IPv6 NAT64 ranges (64:ff9b::/96, 64:ff9b:1::/48), allowing metadata/internal access behind a NAT64 gateway","descriptions":[{"lang":"en","value":"ToolHive is a utility designed to simplify the deployment and management of Model Context Protocol (MCP) servers. Prior to 0.29.1, networking.IsPrivateIP in pkg/networking/utilities.go omits the IPv6 NAT64 prefixes 64:ff9b::/96 and 64:ff9b:1::/48, so NAT64 addresses embedding private, loopback, or link-local IPv4 targets are classified as public and allowed. The most direct attacker-controlled path begins when an external OAuth client supplies a client_id URL that CIMDStorageDecorator.GetClient routes through FetchClientMetadataDocument in pkg/oauthproto/cimd/fetch.go; protectedDialerControl in pkg/networking/http_client.go and validateHost in pkg/skills/gitresolver/reference.go share the defective classification but use operator-controlled or user-controlled destinations. On a ToolHive host behind a NAT64/DNS64 gateway, the gateway translates an allowed address such as 64:ff9b:1::a9fe:a9fe to 169.254.169.254, permitting blind probing of internal TCP or TLS reachability. The attacker-controlled CIMD path requires HTTPS, verifies certificates, and does not reflect response bodies, so the established impact is an internal reachability oracle rather than metadata credential exfiltration; the webhook client is not affected because it does not use this IP guard. This issue is fixed in version 0.29.1."}],"affected":[{"vendor":"stacklok","product":"toolhive","versions":[{"version":"< 0.29.1","status":"affected"}]}],"references":[{"url":"https://github.com/stacklok/toolhive/security/advisories/GHSA-pph6-vfjv-vpjw","name":"https://github.com/stacklok/toolhive/security/advisories/GHSA-pph6-vfjv-vpjw","tags":["x_refsource_CONFIRM"]},{"url":"https://github.com/stacklok/toolhive/commit/26912af453d2040787983dbc9ab93a9019ec0468","name":"https://github.com/stacklok/toolhive/commit/26912af453d2040787983dbc9ab93a9019ec0468","tags":["x_refsource_MISC"]},{"url":"https://github.com/stacklok/toolhive/releases/tag/v0.29.1","name":"https://github.com/stacklok/toolhive/releases/tag/v0.29.1","tags":["x_refsource_MISC"]}],"metrics":[{"cvssV4_0":{"attackVector":"NETWORK","attackComplexity":"LOW","attackRequirements":"PRESENT","privilegesRequired":"NONE","userInteraction":"NONE","vulnConfidentialityImpact":"LOW","vulnIntegrityImpact":"NONE","vulnAvailabilityImpact":"NONE","subConfidentialityImpact":"NONE","subIntegrityImpact":"NONE","subAvailabilityImpact":"NONE","baseScore":2.9,"baseSeverity":"LOW","vectorString":"CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N/E:P","version":"4.0"}}],"problemTypes":[{"descriptions":[{"cweId":"CWE-918","lang":"en","description":"CWE-918: Server-Side Request Forgery (SSRF)","type":"CWE"}]}],"providerMetadata":{"shortName":"GitHub_M","orgId":"a0819718-46f1-4df5-94e2-005712e83aaa","dateUpdated":"2026-09-15T15:47:39.377Z"},"source":{"advisory":"GHSA-pph6-vfjv-vpjw","discovery":"UNKNOWN"}},"adp":[{"title":"CISA ADP Vulnrichment","metrics":[{"other":{"type":"ssvc","content":{"timestamp":"2026-09-15T16:12:58.689222Z","id":"CVE-2026-54450","options":[{"Exploitation":"none"},{"Automatable":"no"},{"Technical Impact":"partial"}],"role":"CISA Coordinator","version":"2.0.3"}}}],"providerMetadata":{"shortName":"CISA-ADP","orgId":"134c704f-9b21-4f2e-91b3-4a467353bcc0","dateUpdated":"2026-09-15T16:13:16.652Z"}}]}}}