CVE-2026-58196
ToolHive is a utility designed to simplify the deployment and management of Model Context Protocol (MCP) servers. Prior to 0.31.0, remote.Ha…
ToolHive is a utility designed to simplify the deployment and management of Model Context Protocol (MCP) servers. Prior to 0.31.0, remote.Handler.Authenticate in pkg/auth/remote/handler.go invokes discovery.DetectAuthenticationFromServer in pkg/auth/discovery/discovery.go, whose host-side HTTP clients trust remote-server-controlled authentication discovery destinations, follow redirects without host or scheme restrictions, and do not consistently block private addresses. A malicious or compromised remote MCP server can place a resource_metadata URL in WWW-Authenticate for ParseWWWAuthenticate to extract, after which FetchResourceMetadata, OIDC issuer discovery, and well-known discovery can issue GET requests to link-local, RFC1918, or other internal services outside the server's container. The user connects to a server that the user intends to use, but the server controls the internal destination; this path does not depend on the separate NAT64 guard omission because the affected clients did not invoke IsPrivateIP, and it differs from the DCR resolver path that already refused redirects. The demonstrated primitive reaches internal-only HTTP services and reachability or error oracles, and can retrieve AWS metadata credentials where IMDSv1 accepts an unauthenticated GET, while IMDSv2 and GCP metadata prerequisites are not satisfied by the demonstrated request. This vulnerability is fixed in 0.31.0.
Why it matters
- ▸ Remotely exploitable over the network — no physical or local access required
- ▸ Low attack complexity — no special conditions needed to exploit
- ▸ No authentication required
- ▸ Requires the victim to take an action (e.g. open a file or link)
Apply the vendor patch as soon as it's available or already released. User-awareness training reduces risk here, since exploitation depends on tricking a user into acting.
This analysis is generated from structured CVSS vector data, CISA KEV cross-referencing, and vendor/product category rules — not a manual expert review. Treat it as a starting point, not a substitute for your own assessment.
CVSS Vector Breakdown
EU Vulnerability Database (ENISA)
EUVD is ENISA's EU vulnerability database, still in beta. EPSS is a probabilistic exploitation-likelihood score, not a certainty.
Stay Updated
New CVEs and vulnerability advisories are added continuously as they're disclosed. Subscribe via RSS to get every update the moment it's published — no email or account required.
Subscribe via RSS