# CVE-2026-54450

## Summary

- **CVE ID:** CVE-2026-54450
- **Severity:** LOW
- **CVSS Score:** 2.9 (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)
- **CWE:** CWE-918
- **Published:** Sep 15, 2026
- **Last Modified:** Sep 15, 2026

## 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.

## Affected Products

- stacklok — toolhive (< 0.29.1)

## References

- [CNA](https://github.com/stacklok/toolhive/security/advisories/GHSA-pph6-vfjv-vpjw)
- [CNA](https://github.com/stacklok/toolhive/commit/26912af453d2040787983dbc9ab93a9019ec0468)
- [CNA](https://github.com/stacklok/toolhive/releases/tag/v0.29.1)

## Exploitation Prediction (EPSS)

- **EPSS Score:** 0.32%
- **EPSS Percentile:** 24.4

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_Exported from OnDuty AI Vulnerability Intelligence on 2026-09-17._